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Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 2 Table of Contents Table of Contents Legal information ......................................................................................................... 2 1 Preface ................................................................................................................ 6 2 S7-1200/S7-1500 innovations ........................................................................... 8 2.1 2.2 2.3 2.4 2.5 2.6 2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 Siemens AG 2018 All rights reserved 2.6.6 2.7 2.7.1 2.7.2 2.7.3 2.8 2.8.1 2.8.2 2.8.3 2.8.4 2.8.5 2.9 2.9.1 2.9.2 2.9.3 2.9.4 2.9.5 2.10 2.10.1 2.10.2 2.11 2.12 2.13 2.14 3 Introduction ........................................................................................... 8 Terms ................................................................................................... 8 Programming languages .................................................................... 11 Optimized machine code .................................................................... 11 Block creation ..................................................................................... 12 Optimized blocks ................................................................................ 13 S7-1200: Structure of optimized blocks ............................................. 13 S7-1500: Structure of optimized blocks ............................................. 14 Processor-optimized data storage for S7-1500 ................................. 15 Conversion between optimized and non-optimized tags ................... 18 Parameter transfer between blocks with optimized and nonoptimized access ................................................................................ 19 Communication with optimized data .................................................. 20 Block properties .................................................................................. 21 Block sizes ......................................................................................... 21 Number of organization blocks (OB) .................................................. 21 Block interface - hide block parameters (V14 or higher) ................... 22 New data types for S7-1200/1500 ...................................................... 23 Elementary data types........................................................................ 23 Data type Date_Time_Long ............................................................... 24 Other time data types ......................................................................... 24 Unicode data types ............................................................................. 25 Data type VARIANT (S7-1500 and S7-1200 from FW4.1) ................. 26 Instructions ......................................................................................... 29 MOVE instructions .............................................................................. 29 VARIANT instructions (S7-1500 and S7-1200 FW4.1 and higher) ................................................................................................ 31 RUNTIME ........................................................................................... 32 Comparison of tags from PLC data types (V14 or higher) ................. 33 Multiple assignment (V14 or higher) .................................................. 34 Symbolic and comments .................................................................... 35 Programming editor ............................................................................ 35 Comment lines in watch tables .......................................................... 36 System constants ............................................................................... 37 User constants ................................................................................... 38 Internal reference ID for controller and HMI tags ............................... 39 STOP mode in the event of errors ..................................................... 41 General programming ..................................................................................... 42 3.1 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 3.2.9 3.2.10 Operating system and user program .................................................. 42 Program blocks .................................................................................. 42 Organization blocks (OB) ................................................................... 43 Functions (FC) .................................................................................... 45 Function blocks (FB) .......................................................................... 47 Instances ............................................................................................ 48 Multi-instances ................................................................................... 49 Transferring instance as parameters (V14)........................................ 51 Global data blocks (DB) ..................................................................... 52 Downloading without reinitialisation ................................................... 53 Reusability of blocks........................................................................... 57 Auto numbering of blocks ................................................................... 58 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 3 Table of Contents Siemens AG 2018 All rights reserved 3.3 3.3.1 3.3.2 3.3.3 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.5 3.6 3.6.1 3.6.2 3.6.3 3.6.4 3.6.5 3.6.6 3.6.7 3.7 3.7.1 3.7.2 3.7.3 3.7.4 3.8 3.9 3.10 3.10.1 3.10.2 3.10.3 3.10.4 3.10.5 3.10.6 3.10.7 3.10.8 3.10.9 3.10.10 3.10.11 4 Hardware-independent programming ........................................................... 97 4.1 4.2 4.3 5 Block interface types .......................................................................... 59 Call-by-value ...................................................................................... 59 Call-by-reference ................................................................................ 59 Overview for transfer of parameters ................................................... 60 Memory concept ................................................................................. 60 Block interfaces as data exchange .................................................... 60 Global memory ................................................................................... 61 Local memory ..................................................................................... 62 Access speed of memory areas ......................................................... 63 Retentivity ........................................................................................... 64 Symbolic addressing .......................................................................... 67 Symbolic instead of absolute addressing ........................................... 67 ARRAY data type and indirect field accesses .................................... 69 Formal parameter Array [*] (V14 or higher)........................................ 71 STRUCT data type and PLC data types ............................................ 72 Access to I/O areas with PLC data types ........................................... 75 Slice access ....................................................................................... 76 SCL networks in LAD and FBD (V14 and higher) .............................. 77 Libraries .............................................................................................. 78 Types of libraries and library elements .............................................. 79 Type concept ...................................................................................... 80 Differences between the typifiable objects for CPU and HMI ............ 81 Versioning of a block .......................................................................... 81 Increased performance for hardware interrupts ................................. 86 Additional performance recommendations......................................... 88 SCL programming language: Tips and Tricks .................................... 89 Using call templates ........................................................................... 89 What instruction parameters are mandatory? .................................... 90 Drag-and-drop with entire tag names................................................. 90 Structuring with the keyword REGION (V14 or higher) ...................... 91 Correct use of FOR, REPEAT and WHILE loops .............................. 92 Using CASE instruction efficiently ...................................................... 93 No manipulation of loop counters for FOR loop ................................. 93 FOR loop backwards .......................................................................... 94 Easy creation of instances for calls .................................................... 94 Handling of time tags .......................................................................... 94 Unnecessary IF instruction ................................................................. 96 Data types of S7-300/400 and S7-1200/1500 .................................... 97 No bit memory but global data blocks ................................................ 99 Programming of "Cycle bits"............................................................... 99 STEP 7 Safety in the TIA Portal .................................................................... 100 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.9.1 5.9.2 5.10 5.11 5.12 Introduction ....................................................................................... 100 Terms ............................................................................................... 101 Components of the safety program .................................................. 102 F-runtime group ................................................................................ 103 F signature ....................................................................................... 103 Assigning the PROFIsafe address at the F-I/O ................................ 105 Evaluation of F-I/O ........................................................................... 105 Value status (S7-1200F/1500F) ....................................................... 106 Data types ........................................................................................ 107 Overview........................................................................................... 107 Implicit conversion ............................................................................ 107 F-conform PLC data type ................................................................. 109 TRUE / FALSE ................................................................................. 111 Optimizing the compilation and program runtime ............................ 112 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 4 Table of Contents 5.12.1 5.12.2 5.12.3 5.13 5.14 5.15 5.16 5.17 6 Avoiding of time-processing blocks: TP, TON, TOF ........................ 113 Avoiding deep call hierarchies ......................................................... 113 Avoiding JMP/Label structures ......................................................... 113 Data exchange between standard program and F program ............ 114 Testing the safety program............................................................... 115 STOP mode in the event of F errors ................................................ 116 Migration of safety programs ............................................................ 116 General recommendations for safety ............................................... 116 Automatically generate visualization using the user program ................. 117 6.1 6.2 6.3 6.3.1 6.3.2 6.4 Introduction ....................................................................................... 117 How automatic generation works ..................................................... 118 Controlling the HMI generator .......................................................... 119 Using network comments for control ................................................ 119 Using SiVArc variables for control .................................................... 120 Additional recommendations ............................................................ 121 7 The most important recommendations ....................................................... 122 8 Appendix ........................................................................................................ 123 Service and support ......................................................................... 123 Links and literature ........................................................................... 124 Change documentation .................................................................... 125 Siemens AG 2018 All rights reserved 8.1 8.2 8.3 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 5 1 Preface 1 Preface Objective for the development of the new SIMATIC controller generation * An engineering framework for all automation components (controller, HMI, drives, etc.) * Uniform programming * Increased performance * Complete set of command for every language * Fully symbolic program generation * Data handling also without pointer * Reusability of created blocks Copyright Siemens AG 2018 All rights reserved Objective of the guideline The new controller generation SIMATIC S7-1200 and S7-1500 has an up-to-date system architecture, and together with the TIA Portal offers new and efficient options of programming and configuration. It is no longer the resources of the controller (e.g. data storage in the memory) that are paramount but the actual automation solution itself. This document gives you many recommendations and notes on optimal programming of S7-1200/1500 controllers. Some differences in the system architecture of the S7-300/400, as well as the thus connected new programming options are explained in an easy to understand way. This helps you to create standardized and optimal programming of your automation solutions. The examples described can be universally used for the controllers S7-1200 and S7-1500. Core contents of this programming guideline The following key issues on the TIA Portal are dealt with in this document: * * S7-1200/1500 innovations - Programming languages - Optimized blocks - Data types and instructions Recommendations on general programming - Operating system and user program - Memory concept - Symbolic addressing - Libraries * Recommendations on hardware-independent programming * Recommendations on STEP 7 Safety in TIA Portal * Overview of the most important recommendations Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 6 1 Preface Advantages and benefits Numerous advantages result from applying these recommendations and tips: * Powerful user program * Clear program structures * Intuitive and effective programming solutions Further information When programming SIMATIC controllers, the task of the programmer is to create as clear and readable a user program as possible. Each user uses their own strategy, for example, how to name tags or blocks or the way of commenting. The different philosophies of the programmers create very different user programs that can only be interpreted by the respective programmer. The programming style guide offers you coordinated set of rules for consistent programming. These specifications for example describe a uniform assignment of tags and block names right up to clear programming in SCL. Copyright Siemens AG 2018 All rights reserved You can use these rules and recommendations freely; they serve as a suggestion (not a standard in programming) for consistent programming. Note The programming style guide for S7-1200 and S7-1500 can be found at the following link: https://support.industry.siemens.com/cs/ww/en/view/81318674 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 7 2 S7-1200/S7-1500 innovations 2.1 Introduction 2 S7-1200/S7-1500 innovations 2.1 Introduction In general, the programming of the SIMATIC controllers from S7-300/400 to S71500 has stayed the same. There are the known programming languages such as LAD, FBD, STL, SCL or graph and blocks such as organization blocks (OBs), function blocks (FBs), functions (FCs) or data blocks (DBs). S7-300/400 programs created can be easily implemented on S7-1500 and existing LAD, FBD and SCL programs can be easily implemented on S7-1200 controllers. In addition, there are many innovations that facilitate programming for you and enables powerful and memory-saving code. Copyright Siemens AG 2018 All rights reserved For programs that are implemented for S7-1200/1500 controllers, we recommend not to implement them one-to-one, but also to check new options and if possible, to use them. The extra effort is often limited and you will receive a program code that is, for example, Note * optimal for memory and runtime for the new CPUs, * easier to understand, * and easier to maintain. Information for the migration of S7-300/S7-400 to S7-1500 can be found in the following entry: https://support.industry.siemens.com/cs/ww/en/view/109478811 2.2 Terms General terms in the TIA Portal Some terms have change to enable easier handling with the TIA Portal. Figure 2-1: New terms in the TIA Portal STEP 7 V5.x STEP 7 (TIA Portal) Symbol table PLC tags UDT PLC data types Tag table Watch table Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 8 2 S7-1200/S7-1500 innovations 2.2 Terms Terms for tags and parameters When dealing with tags, functions, and function blocks, many terms are repeatedly used differently or even incorrectly. The following figure clarifies these terms. Figure 2-2: Terms for tags and parameters Globaler DB 2 FC / FB 1 3 4 Table 2-1: Terms for Tags and parameters Copyright Siemens AG 2018 All rights reserved Term Description 1. Tags Tags are labeled by a name/identifier and use an address in the memory of the controller. Tags are always defined with a certain data type (Bool, Integer, etc.): * PLC tags * Individual tags in data blocks * Complete data blocks 2. Tag value Tag values are values stored in a tag (for example, 15 as value of an integer tag). 3. Actual parameter Actual parameters are tags interconnected at the interfaces of instructions, functions, and function blocks. 4. Formal parameters (transfer parameter, block parameter) Formal parameters are the interface parameters of instructions, functions, and function blocks (Input, Output, InOut, and Ret_Val). Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 9 2 S7-1200/S7-1500 innovations 2.2 Terms Note More information can be found in the following entries: What entries are available on the internet for the migration to STEP 7 (TIA Portal) and WinCC (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/56314851 What system requirements have to be fulfilled to migrate a STEP 7 V5.x project in STEP 7 Professional (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/62100731 PLC migration to S7-1500 with STEP 7 (TIA Portal) https://support.industry.siemens.com/cs/ww/en/view/67858106 How can you program efficiently and performant in STEP 7 (TIA Portal) for S71200/S7-1500? https://support.industry.siemens.com/cs/ww/en/view/67582299 Copyright Siemens AG 2018 All rights reserved Why is it not possible to mix register passing and explicit parameter transfer with the S7-1500 in STEP 7 (TIA Portal)? Among other topics, the migration of STL programs to S7-1500 is described in this entry. https://support.industry.siemens.com/cs/ww/en/view/67655405 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 10 2 S7-1200/S7-1500 innovations 2.3 Programming languages 2.3 Programming languages Different programming languages are available for the programming of a user program. Each language has its own advantages that can be used flexibly depending on application. Thus, each block in the user program can be created in any programming language. Table 2-2: Programming languages Programming language Note S7-1200 S7-1500 Ladder diagram (LAD) yes yes Function block diagram (FBD) yes yes Structured Control Language (SCL) yes yes Graph no yes Statement list (STL) no yes More information can be found in the following entries: Copyright Siemens AG 2018 All rights reserved SIMATIC S7-1200 / S7-1500 Comparison List for Programming Languages Based on the International Mnemonics https://support.industry.siemens.com/cs/ww/en/view/86630375 What should you watch out for when migrating an S7-SCL program in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/59784005 Which instructions can you not use in an SCL program in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/58002709 How do you define the constants in an S7-SCL program in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/52258437 2.4 Optimized machine code TIA Portal and S7-1200/1500 enable an optimized runtime performance in every programming language. All languages are compiled directly in machine code in the same way. Advantages * All programming languages have the same level of performance (for the same access types) * No reduction of performance through additional compilation with interim step via STL Properties In the following figure, the difference in the compilation of S7-programs in machine code is displayed. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 11 2 S7-1200/S7-1500 innovations 2.5 Block creation Figure 2-3: Machine code creation with S7-300/400/WinAC and S7-1200/1500 S7-1200/1500 S7-300/400/WinAC SCL LAD FBD SCL LAD FBD STL (only S7-1500) STL Copyright Siemens AG 2018 All rights reserved Maschine code S7-300/400/WinAC 2.5 Maschine code S7-1200/1500 * For S7-300/400/WinAC controllers LAD and FBD programs are first compiled in STL before machine code is created. * For S7-1200/1500 controllers all programming languages are directly compiled in machine code. Block creation All blocks such as OBs, FBs and FCs can be directly programmed in the desired programming language. Therefore no source has to be created for SCL programming. Only select the block and SCL as programming language. You can then program the block directly. Figure 2-4: Dialog "Add new Block" Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 12 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks 2.6 Optimized blocks S7-1200/1500 controllers have an optimized data storage. In optimized blocks all tags are automatically sorted according to their data type. The sorting ensures that data gaps between the tags are reduced to a minimum and that the tags are stored access-optimized for the processor. Non-optimized blocks are only available for compatibility reasons in S7-1200/1500 controllers. Copyright Siemens AG 2018 All rights reserved Advantages 2.6.1 * Access always takes place as quickly as possible since the data storage is optimized by the system and independent of the declaration. * No danger of inconsistencies due to faulty, absolute access, since access is generally symbolic * Declaration changes do not lead to access errors since, for example, HMI access is symbolic. * Individual tags can be specifically defined as retentive. * No settings required in the instance data block. Everything is set in the assigned FB (for example, retentivity). * Storage reserves in the data block enables changes without loss of current values (see chapter 3.2.8 Downloading without reinitialisation). S7-1200: Structure of optimized blocks Figure 2-5: Optimized blocks for S7-1200 Standard block Bits Standard 0 0 1 2 2 4 Optimized 5 6 0 7 1 2 3 B1 X2 X3 3 4 5 6 7 W1 B y t e s W2 B1 W1 5 6 4 X1 1 B y t e s 3 Optimized block Bits X1 X2 X3 X4 X3 7 8 W2 9 Properties * No data gaps are formed since larger tags are located at the start of a block and smaller ones at the end. * There is only symbolic access for optimized blocks. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 13 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks 2.6.2 S7-1500: Structure of optimized blocks Figure 2-6: Optimized blocks for S7-1500 Standard block Bits Standard 0 0 1 2 3 2 Optimized 4 5 6 0 7 2 3 4 5 6 7 W1 B1 X2 B y t e s X3 3 4 W1 5 6 1 X1 1 B y t e s Optimized block Bits W2 B1 X1 X2 X4 X3 7 X4 8 W2 Reserve 9 Copyright Siemens AG 2018 All rights reserved Figure 2-7: Memory mapping for optimized blocks Optimized 4 Byte are always read at once DW 0 16 W W DW W B 1 W W B B B B X X X Reserve 32 B y t e s W 48 64 80 96 DW 102 128 W B X X DW DW W W 2 Reserve 144 1. Structures are located separately and can therefore be copied as block. 2. Retentive data is located in a separate area and can be copied as block. In the event of a loss of voltage this data is saved internally in the CPU. "MRES" resets this data to the start values located in the load memory. Properties * No data gaps are formed since larger tags are located at the start of a block and smaller ones at the end. * Faster access due to processor-optimized storage (all tags are stored in a way so that the processor of the S7-1500 can directly read or write them with only one machine command). * Boolean tags are stored as byte for faster access. Thus, the controller does not have to mask the access. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 14 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks 2.6.3 * Optimized blocks have a storage reserve for loading in running operation (see chapter 3.2.8 Downloading without reinitialisation). * There is only symbolic access for optimized blocks. Processor-optimized data storage for S7-1500 For reasons of compatibility to the first SIMATIC controllers, the principle of the "Big Endian" data storage was accepted in the S7-300/400 controllers. Based on the changed processor architecture, the new S7-1500 controller generation always accesses 4 byte (32 bit) in "Little-Endian" sequence. Thus the following properties result on the system side. Figure 2-8: Data access of a S7-1500 controller Bits Standard 0 1 2 4 5 6 7 Conversion for processor access: Big Little Endian 1 Copyright Siemens AG 2018 All rights reserved 3 BYTE 0 B y t e s Optimized block max. 16MB 2 0 3 1 4 2 5 3 6 X REAL Big-Endian 1 X 2 7 8 0 9 1 Copying requires time due to resorting! Standard block max. 64kB Bits Optimized 0 1 2 3 3 2 B y t e s REAL 1 4 5 6 7 Best possible processor data storage: No conversion required. 0 Little-Endian 1 1 WORD 0 Little-Endian BYTE X X WORD Big-Endian 2 Reserve Table 2-3: Data access of a S7-1500 controller Standard block Optimized block 1. In the event of an unfavorable offset, the controller requires 2x16 bit access to read a 4 byte value (for example, REAL value). In addition the bytes have to be turned. The controller stores the tags accessoptimized. Access is with 32 bit (REAL). Turning the bytes is not required. 2. The entire byte is read and masked per bit access. The complete byte is blocked for any other access. Each bit is assigned a byte. The controller does not have to mask the byte when accessing. 3. Maximum block size is 64kB. Maximum block size can be up to 16MB. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 15 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks Recommendation * In general, only use optimized blocks. * - You do not require absolute addressing and you can always address with symbolic data (object-related). Indirect addressing is also possible with symbolic data (see chapter 3.6.2 ARRAY data type and indirect field accesses). - Processing optimized blocks in the controller is considerably faster than for standard blocks. Avoid the copying/assigning of data between optimized and non-optimized blocks. The data conversion required between source and target format requires high processing time. Example: Setting optimized block access Copyright Siemens AG 2018 All rights reserved By default, the optimized block access is enabled for all newly created blocks for S7-1200/1500. Block access can be set for OBs, FBs and global DBs. For instance DBs, the setting derives from the respective FB. Block access is not automatically reset if a block is migrated from a S7-300/400 controller to a S7-1200/1500. You can later change the block access to "Optimized block access". After changing the block access, you have to recompile the program. If you change FBs to "Optimized block access", the assigned instance data blocks are automatically updated. Follow the instructions to set the optimized block access. Table 2-4: Setting optimized block access Step Instruction 1. Click the "Maximizes/minimizes the Overview" button in the project tree. 2. Navigate to "Program blocks". Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 16 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks Step 3. Instruction Here, you see all blocks in the program and whether they are optimized or not. In this overview the status "Optimized block access" can be conveniently changed. Note: Instance data blocks (here "Function_block_1_DB") inherit the status "optimized" from the associated FB. This is why the "optimized" setting can only be changed on the FB. After the compilation of the project, the DB takes on the status depending on the associated FB. Copyright Siemens AG 2018 All rights reserved Display of optimized and non-optimized blocks in the TIA Portal In the two following figures the differences between an optimized and a nonoptimized instance DB can be seen. For a global DB there are the same differences. Figure 2-9: optimized data block (without offset) Figure 2-10: non-optimized data block (with offset) Table 2-5: Difference: Optimized and non-optimized data block Optimized data block Non-optimized data block Optimized data blocks are addressed symbolically. Therefore no "offset" is shown. For non-optimized blocks the "offset" is shown and can be used for addressing. In the optimized block you can declare each tag individually with "Retain". In non-optimized blocks only all or no tag can be declared with "Retain". Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 17 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks The retentivity of tags of a global DB is directly defined in the global DB. By default, non-retain is preset. Define the retentivity of tags in an instance in the function block (not the instance DB). These settings are therefore valid for all instances of this FB. Access types for optimized and non-optimized data blocks In the following table all access types for blocks are displayed. Table 2-6: Access types Copyright Siemens AG 2018 All rights reserved Access type Optimized block Non-optimized block Symbolic yes yes Indexed (fields) yes yes Slice access yes yes AT instruction no (Alternative: slice access) yes Direct absolute no (Alternative: ARRAY with INDEX) yes no (Alternative: VARIANT / ARRAY with index) yes yes no Indirect absolute (pointer) Load without reinitialization Note More information can be found in the following entries: What types of access are available in STEP 7 (TIA Portal) to access data values in blocks and what should you watch out for with the differences between the types? https://support.industry.siemens.com/cs/ww/en/view/67655611 Which properties should you watch out for in STEP 7 (TIA Portal) for the instructions "READ_DBL" and "WRIT_DBL" when using DBs with optimized access? https://support.industry.siemens.com/cs/ww/en/view/51434747 2.6.4 Conversion between optimized and non-optimized tags It is generally recommended to work with optimized tags. However, if in individual cases, you want to keep your programming so far, there will be a mix of optimized and non-optimized data storage in the program. The system knows the internal storage of each tag, irrelevant whether structured (derived from an individually defined data type) or elementary (INT, LREAL, ...). For assignments with the same type between two tags with different memory storage, the system converts automatically. This conversion requires performance for structured tags and should therefore be avoided, if possible. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 18 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks 2.6.5 Parameter transfer between blocks with optimized and non-optimized access When you transfer structures to the called block as in/out parameters (InOut), they are transferred by default as reference (see chapter 3.3.2 Call-by-reference). However, this is not the case if one of the blocks has the property "Optimized access" and the other block the property "Default access". In this case, all parameters are generally transferred as copy (see chapter 3.3.1 Call-by-value). In this case the called block always works with the copied values. During block processing, these values may be changed and they are copied back to the original operand, after processing of the block call. This may cause problems if the original operands are changed by asynchronous processes, for example, by HMI access or interrupt OBs. If the copies are copied back to the original operands after the block processing, the asynchronously performed changes on the original operands are overwritten. Copyright Siemens AG 2018 All rights reserved Note More information can be found in the following entries: Why is data of the HMI system or the web server sometimes overwritten in the S7-1500? https://support.industry.siemens.com/cs/ww/en/view/109478253 Recommendation * Always set the same access type for the two blocks that communicate with each other. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 19 2 S7-1200/S7-1500 innovations 2.6 Optimized blocks 2.6.6 Communication with optimized data The interface (CPU, CM) transfers the data in the way it is arranged (irrespective of whether it is optimized or non-optimized). Figure 2-11: CPU-CPU communication Compatible data transfer (byte stream) Send CPU Copyright Siemens AG 2018 All rights reserved 0A B1 32 39 Send data can be: * optimized * not optimized * Tag (any type) * Buffer (byte array) 4F 6D 7A Receive CPU ... FF Receive data can be: * optimized * not optimized * Tag (any type) * Buffer (byte array) Example * A tag with PLC data type (data record) shall be passed on to a CPU. * In the send CPU the tag is interconnected as actual parameter with the communication block (TSEND_C). * In the receive CPU the receive data is assigned to a tag of the same type. * In this case symbolic work on the received data can be directly continued. Note Any tags or data blocks can be used as data records (derived from PLC data types). Note It is also possible to define the send and receive data differently: Send data optimized Receive data --> non-optimized --> non-optimized optimized The controller automatically makes sure that the data transfer and storage is correct. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 20 2 S7-1200/S7-1500 innovations 2.7 Block properties 2.7 Block properties 2.7.1 Block sizes For S7-1200/1500 controllers the maximum size of blocks in the main memory was noticeably enlarged. Table 2-7: Block sizes Max. size and number (without consideration of memory size) DB FC / FB Copyright Siemens AG 2018 All rights reserved FC / FB / DB S7-300/400 S7-1200 S7-1500 Max. size 64 kB 64 kB 64 kB 16 MB (optimized CPU1518) Max. number 16.000 65.535 65.535 Max. size 64 kB 64 kB 512 kB Max. number 7.999 65.535 65.535 Max. number 4.096 (CPU319) 6.000 (CPU412) 1.024 10.000 (CPU1518) Recommendation 2.7.2 * Use DBs for S7-1500 controllers as data container of very large data volumes. * You can store data volumes of > 64 kB with S7-1500 controllers in an optimized DB (max. size 16 MB). Number of organization blocks (OB) With OBs a hierarchical structure of the user program can be created. There are different OBs available for this. Table 2-8: Number of organization blocks Organization block type S7-1200 S7-1500 Benefits Cyclic and startup OBs 100 100 Modularization of the user program Hardware interrupts 50 50 Separate OB for each event possible 20 Modularization of the user program 20 Modularization of the user program 20 Modularization of the user program Delay interrupts 4* Cyclic interrupts Clocked interrupts no * As of firmware V4, 4 delay interrupts and 4 cyclic interrupts are possible. Recommendation * Use OBs in order to structure the user program hierarchically. * Further recommendations for the use of OBs can be found in chapter 3.2.1 Organization blocks (OB). Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 21 2 S7-1200/S7-1500 innovations 2.7 Block properties 2.7.3 Block interface - hide block parameters (V14 or higher) When calling the block, block parameters can be specifically displayed or hidden. Here, you have three options that you can configure individually for each formal parameter. * "Show" * "Hide" * "Hide if no parameter is assigned" * Better overview for blocks with many optional parameters * Can be used for: Advantages Properties - FCs, FBs - In, Out, InOut Copyright Siemens AG 2018 All rights reserved Example Figure 2-12: Hide block parameters Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 22 2 S7-1200/S7-1500 innovations 2.8 New data types for S7-1200/1500 2.8 New data types for S7-1200/1500 S7-1200/1500 controllers support new data types to make programming more convenient. With the new 64 bit data types, considerably larger and more precise values can be used. Note More information can be found in the following entry: In STEP 7 (TIA Portal), how do you convert the data types for the S71200/1500? https://support.industry.siemens.com/cs/ww/en/view/48711306 2.8.1 Elementary data types Copyright Siemens AG 2018 All rights reserved Table 2-9: Integer data types Type Size Value range USint 8 bit 0 .. 255 SInt 8 bit -128 .. 127 UInt 16 bit 0 .. 65535 UDInt 32 bit 0 .. 4.3 Mio ULInt* 64 bit 0 .. 18.4 Trio (1018) LInt* 64 bit -9.2 Trio .. 9.2 Trio LWord 64 bit 16#0000 0000 0000 0000 to 16# FFFF FFFF FFFF FFFF * only for S7-1500 Table 2-10: Floating-point data types Type Note Size Value range Real 32 bit (1 bit prefix, 8 bit exponent, 23 bit mantissa), precision 7 places after the comma -3.40e+38 .. 3.40e+38 LReal 64 bit (1 bit prefix, 11 bit exponent, 52 bit mantissa), precision 15 places after the comma -1.79e+308 .. 1.79e+308 More information can be found in the following entries: Why, in STEP 7 (TIA Portal), is the result of the DInt Addition in SCL not displayed correctly? https://support.industry.siemens.com/cs/ww/en/view/98278626 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 23 2 S7-1200/S7-1500 innovations 2.8 New data types for S7-1200/1500 2.8.2 Data type Date_Time_Long Table 2-11: Structure of DTL (Date_Time_Long) Year Month Day Weekday Hour Minute Second Nanosecond DTL always reads the current system time. Access to the individual values is by the symbolic names (for example, My_Timestamp.Hour) Advantages * All subareas (for example, Year, Month, ...) can be addressed symbolically. Recommendation Use the new data type DTL instead of LDT and address it symbolically (for example My_Timestamp.Hour). Copyright Siemens AG 2018 All rights reserved Note More information can be found in the following entries: In STEP 7 (TIA Portal), how can you input, read out and edit the date and time for the CPU modules of S7-300/S7-400/S7-1200/S7-1500? https://support.industry.siemens.com/cs/ww/en/view/43566349 Which functions are available in STEP 7 V5.5 and in TIA Portal for processing the data types DT and DTL? https://support.industry.siemens.com/cs/ww/en/view/63900229 2.8.3 Other time data types Table 2-12: Time data types (only S7-1500) Type Size Value range LTime 64 Bit LT#-106751d23h47m16s854ms775us808ns to LT#+106751d23h47m16s854ms775us807ns 64 Bit LTOD#00:00:00.000000000 to LTOD#23:59:59.999999999 LTIME_OF_DAY Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 24 2 S7-1200/S7-1500 innovations 2.8 New data types for S7-1200/1500 2.8.4 Unicode data types With the help of the data types WCHAR and WSTRING Unicode characters can be processed. Table 2-13: Time data types (only S7-1500) Type Size WCHAR 2 Byte - (4 + 2*n) Byte Preset value: 0 ..254 characters Max. Value: 0 ..16382 WSTRING Value range n = length of string Properties * Processing of characters in, for example, Latin, Chinese or other languages. * Line breaks, form feed, tab, spaces * Special characters: Dollar signs, quotes * WCHAR#`a` * WSTRING#`Hello World!` Copyright Siemens AG 2018 All rights reserved Example Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 25 2 S7-1200/S7-1500 innovations 2.8 New data types for S7-1200/1500 2.8.5 Data type VARIANT (S7-1500 and S7-1200 from FW4.1) A parameter from the type VARIANT is a pointer that can point to tag of different data types. In contrast to the ANY pointer, VARIANT is a pointer with type test. This means that the target structure and source structure are checked at runtime and have to be identical. VARIANT, for example, is used for communication blocks (TSEND_C) as input. Figure 2-13: Data type VARIANT as input parameters for instruction TSEND_C Copyright Siemens AG 2018 All rights reserved VARIANT Here the structure is checked to TCON_IP_v4 Advantages * Integrated type test prevents faulty access. * The code can be more easily read through the symbolic addressing of the variant tags. * Code is more efficiently and within a shorter time. * Variant pointers are clearly more intuitive than ANY pointers. * The right type of variant tags can be used directly with the help of system functions. * Flexible and performant transfer of different structured tags is possible. Properties In a comparison between ANY and variant, the properties can be seen. Table 2-14: Comparison ANY and variant ANY Variant Requires 10 byte memory with defined structure Does not require a main memory for the user Initialization either via assignment of the data area or by filling the ANY structure Initialization by assigning the data area or system instruction Non-typed - type of an interconnected structure cannot be recognized Typed - interconnected type and for arrays the length can also be determined Partly typed - for arrays the length can also be determined VARIANT can be evaluated and also created via system instructions Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 26 2 S7-1200/S7-1500 innovations 2.8 New data types for S7-1200/1500 Recommendation * Check where before you had to use the ANY pointer. In many cases a pointer is no longer necessary (see following table). * Use the data type VARIANT only for indirect addressing when the data types are only determined at program runtime. * - Use the data type VARIANT as InOut formal parameter to create generic blocks that are independent from the data type of the actual parameters (see example in this chapter). - Use the VARIANT data type instead of the ANY pointer. Errors are detected early on due to the integrated type test. Due to the symbolic addressing, the program code can be easily interpreted. - Use the variant instruction, for example, for type identification (see following example and chapter 2.9.2 VARIANT instructions ) Use the index for arrays instead of addressing the array elements via ANY (see chapter 3.6.2 ARRAY data type and indirect field accesses). Table 2-15: Comparison ANY pointer and simplifications Copyright Siemens AG 2018 All rights reserved What are ANY pointers used for? Note Simplification with S7-1200/1500 Programming functions that can process different data types Functions with variant pointer as InOut parameter for blocks (see following example) Processing of arrays * for example, reading, initializing, copying of elements of the same type Default array functions * Reading and writing with #myArray[#index] (see chapter 3.6.2 ARRAY data type and indirect field accesses) * Copying with MOVE_BLK (see chapter 2.9.1 MOVE instructions) * Transferring structures as InOut parameters * see chapter 3.3.2 Call-by-reference Transferring structures and performant processing via absolute addressing for example, transferring userdefined structures via ANY pointer to functions If values of non-structured VARIANT tags are to be copied, you can also use VariantGet instead of MOVE_BLK_VARIANT (chapter 2.9.2 VARIANT instructions ). Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 27 2 S7-1200/S7-1500 innovations 2.8 New data types for S7-1200/1500 Example With the data type VARIANT it is possible to identify data types in the user program and to respond to them accordingly. The following code of the FCs "MoveVariant" shows a possible programming. * The InOut formal parameter "InVar" (data type VARIANT) is used to show a tag independent from the data type. * The data type of the actual parameter is detected with the "Type_Of" instruction * Depending on the data type, the tag value is copied with the "MOVE_BLK_VARIANT" instruction to the different output formal parameters. * If the data type of the actual parameter is not detected, the block will output an error code. Copyright Siemens AG 2018 All rights reserved Figure 2-14: Formal parameter of the FC "MoveVariant" CASE TypeOf(#inOutVariant) OF // Check datatypes Int: // Move Integer #MoveVariant := MOVE_BLK_VARIANT(SRC := #inOutVariant, COUNT := 1, SRC_INDEX := 0, DEST_INDEX := 0, DEST => #outInteger); Real: // Move Real #MoveVariant := MOVE_BLK_VARIANT(SRC := #inOutVariant, COUNT := 1, SRC_INDEX := 0, DEST_INDEX := 0, DEST => #outReal); typeCustom: // Move outTypeCustom #MoveVariant := MOVE_BLK_VARIANT(SRC := #inOutVariant, COUNT := 1, SRC_INDEX := 0, DEST_INDEX := 0, DEST => #outTypeCustom); ELSE // Error, no sufficient datatype #MoveVariant := WORD_TO_INT(#NO_CORRECT_DATA_TYPE); // 80B4: Error-Code of MOVE_BLK_VARIANT: Data types do not correspond END_CASE; Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 28 2 S7-1200/S7-1500 innovations 2.9 Instructions 2.9 Instructions The TIA Portal supports the programmer with ready instructions (bit logic, times, counter, comparator...). Note Further functions can be downloaded in the following entry: Library with general functions for (LGFP) for STEP 7 (TIA Portal) and S7-1200 / S7-1500 https://support.industry.siemens.com/cs/ww/en/view/109479728 2.9.1 MOVE instructions In STEP 7 (TIA Portal) the following MOVE instructions are available. The MOVE_BLK_VARIANT instruction is new for S7-1200/1500. Table 2-16: Move instructions Copyright Siemens AG 2018 All rights reserved Instruction MOVE Usage Copy value Properties * * * * MOVE_BLK Copy array * * * * UMOVE_BLK Copies array without interruption * * MOVE_BLK_VARIANT (S7-1500 and S7-1200 FW4.1 or higher) Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 Copy array * * * * Copies the content of the parameter on the input IN to the parameter of the output OUT. The parameters on the input and output must be of the same data type. Parameters can also be structured tags (PLC data types). Copies complete arrays and structures. Copies the content of an array to another array. Source and target array must be of the same data type. Copies complete arrays and structures. Copies several array elements with structures as well. In addition, start and number of elements can be specified. Copies the content of an array consistently without the risk of the OB interrupting the copying process. Source and target array must be of the same data type. Copies one or several structured tag(s) (PLC data types) Recognizes data types at runtime Supplies detailed error information Apart from the elementary and structured data types, PLC data types, arrays, and array DBs are also supported. 29 2 S7-1200/S7-1500 innovations 2.9 Instructions Instruction Serialize (S7-1500 and S7-1200 FW4.1 or higher) Deserialize (S7-1500 and S7-1200 FW4.1 or higher) Usage converts structured data into a byte array Properties * * converts one byte array into one or several structure/s * * Several data records can be combined into a single byte array and, for example, be sent to other devices as a message frame. Input and output parameters can be transferred as data type Variant. Application case I-Device: The I device receives several data records in the input area which are copied to different structures. Several data records can be combined into a single byte array. Deserialize enables copying these to different structures. Copyright Siemens AG 2018 All rights reserved Figure 2-15: Serialize and deserialize (S7-1500 and S7-1200 FW4.1 or higher) Array[0..7] of Byte Byte0 Byte1 . . . Byte7 Serialize Struct3 Struct2 Struct1 Int Real Uint . . . Deserialize Properties Instructions such as "Serialize", "Deserialize", "CMP" (comparator) and "MOVE: copy value" can process very large and complex structured tags. In the process, the CPU analyses the tag structure at runtime. Processing time depends on the following properties of the tag structure to be processed: * Complexity of the structure * Number of structures without the use of PLC data types * Array of byte can be saved in optimized blocks (V14 or higher). Recommendation * Declare the structures with the help of PLC data types instead of with "STRUCT" * Reduce the number of structures used: - Avoid, for example, multiple declaration of very similarly made up structures. Summarize them in one single structure. - When many elements of the structure have the same data type, use the data type ARRAY, if possible. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 30 2 S7-1200/S7-1500 innovations 2.9 Instructions * Note Generally, you need to distinguish between MOVE, MOVE_BLK and MOVE_BLK_VARIANT - Use the MOVE instruction to copy complete structures. - Use the MOVE_BLK instruction to copy parts of an ARRAY of a known data type. - Only use the MOVE_BLK_VARIANT instruction if you wish to copy parts of ARRAYs with data types which are only known during program run-time. UMOVE_BLK: The copy process cannot be interrupted by another activity of the operating system. Therefore, the alarm reaction times of the CPU might increase during processing of the instruction "Copy array without interruption". For the complete description of the MOVE instructions, please refer to the TIA Portal Online Help. Note More information can be found in the following entries: Copyright Siemens AG 2018 All rights reserved How do you copy memory areas and structured data in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/42603881 2.9.2 VARIANT instructions (S7-1500 and S7-1200 FW4.1 and higher) Table 2-17: Move instructions Instruction Usage Properties MOVE instructions VariantGet Read value This instruction enables you to read the value of a tag pointing to a VARIANT. VariantPut Write value This instruction enables you to write the value of a tag pointing to a VARIANT. Counting elements With this instruction you poll the number of ARRAY elements of a tag pointing to a VARIANT. TypeOf() (only SCL) Determining the data type Use this instruction to poll the data type of a tag pointing to a VARIANT. TypeOfElements() (only SCL) Determining the array data type Use this instruction to poll the data type of the ARRAY elements of a tag pointing to a VARIANT. Enumeration CountOfElements Comparator instructions Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 31 2 S7-1200/S7-1500 innovations 2.9 Instructions Instruction Usage Properties Comparator instructions Note VARIANT_TO_DB_ANY (only SCL) Determining the data block number This instruction queries the data block number of an instance data block of a PLC data type, system data type or array DB. DB_ANY_TO_VARIANT (only SCL) Created from a data block of a variant tag. This instruction creates the variant tag of an instance data block of a PLC data type, system data type or array DB. For more VARIANT instructions, please refer to the online help of the TIA Portal. Properties Due to their complex algorithm, variant instructions require a longer processing time then direct instructions. Copyright Siemens AG 2018 All rights reserved Recommendation 2.9.3 * If possible, do not use variant instructions in loops (FOR, WHILE...) in order to prevent an unnecessary increase of cycle time. * Do not use a loop via the elements to copy an array, but the direct assignment of the complete array. RUNTIME The "RUNTIME" instruction measures the runtime of the entire program, individual blocks or command sequences. You can call this instruction in LAD, FBD, SCL and in STL (only S7-1500). Note More information can be found in the following entry: With S7-1200/S7-1500, how do you measure the total cycle time of an organization block? https://support.industry.siemens.com/cs/ww/en/view/87668055 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 32 2 S7-1200/S7-1500 innovations 2.9 Instructions 2.9.4 Comparison of tags from PLC data types (V14 or higher) Two tags of the same PLC data type can be checked for similarities or dissimilarities. Copyright Siemens AG 2018 All rights reserved Figure 2-16: Comparison of tags from PLC data types in LAD Advantages * Symbolic programming with structured tags * Comparison with optimum performance * Comparison is possible in LAB, FBD, STL. * Comparison directly possible in STL instruction. Example Figure 2-17: Comparison of tags from PLC data types in STL instructions IF #motor1 = #motor2 THEN // Statement section IF ; END_IF; Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 33 2 S7-1200/S7-1500 innovations 2.9 Instructions 2.9.5 Multiple assignment (V14 or higher) Advantages Multiple assignment enables optimum programming for several tags (e.g., for initializations). Example Copyright Siemens AG 2018 All rights reserved #statFillLevel := #statTemperature := #tempTemperature := 0.0; Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 34 2 S7-1200/S7-1500 innovations 2.10 Symbolic and comments 2.10 Symbolic and comments 2.10.1 Programming editor Advantages You can make the code easy to understand and readable for your colleagues by using symbolic names and comments in your program. The complete symbolic is saved together with the program code during the download to the controller and therefore allows fast maintenance of the plant even when no offline project is available. Recommendation * Use the comments in the programs in order to improve readability. Network title comments are visible even if networks are collapsed. * Design the program code in a way so that colleagues can also understand the program straight away. Copyright Siemens AG 2018 All rights reserved In the following example you can see the extensive options for commenting the program in the editors. Example In the following figure you can see the options for commenting in the LAD editor (same functionality in FDB). Figure 2-18: Commenting in the user program (LAD) 1 2 3 4 The following comments are possible: 1. Block comment 2. Network title comment 3. Network comment 4. Comment on instructions, blocks and functions (open, close, etc.) Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 35 2 S7-1200/S7-1500 innovations 2.10 Symbolic and comments In the programming languages SCL and STL, it can be commented with // in every row. Example statFillingLevel := statRadius * statRadius * PI * statHight; // Calculating the filling level for medium tank Note For further information, refer to the following entry: In STEP 7 (TIA Portal), why are the display texts, titles and comments no longer displayed after opening the project in the block editor? https://support.industry.siemens.com/cs/ww/en/view/41995518 2.10.2 Comment lines in watch tables Advantages Copyright Siemens AG 2018 All rights reserved * For better structuring it is possible to create comment lines in the watch table. Recommendation * Always use comment lines and sub-divide your watch table. * Please also comment on the individual tags. Example Figure 2-19: Watch table with comment lines Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 36 2 S7-1200/S7-1500 innovations 2.11 System constants 2.11 System constants For S7-300/400 controllers the identification of hardware and software components is performed by logic address or diagnostic addresses. For S7-1200/1500 the identification is by system constants. All hardware and software components (e.g., interfaces, modules, OBs, ...) of the S7-1200/1500 controllers have their own system constants. The system constants are automatically created during the setup of the device configuration for the central and distributed I/O. Advantages * You can address via module names instead of hardware identification. Recommendation * Assign function-related module names in order to identify the module easily during programming. Copyright Siemens AG 2018 All rights reserved Example In the following example you can see how system constants are used in the user program. Figure 2-20: "System constants" in the user program 2 1 3 1. System constants of a controller can be found in the "PLC tags - Default tag table" folder. 2. The system constants are in a separate list in the "Default tag table". 3. In this example the symbolic name "RobotArmLeft" was assigned for a DI module. You can also find the module under this name in the system constant table. In the user program "RobotArmLeft" is interconnected with the "GET_DIAG" diagnostic block. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 37 2 S7-1200/S7-1500 innovations Copyright Siemens AG 2018 All rights reserved 2.12 User constants Note Open the "Device configuration" to quickly find the system constant for each device. Note More information can be found in the following entries: What meaning do the system constants have for the S7-1200/1500 in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/78782835 2.12 User constants Constant values can be saved with the help of user constants. Generally, there are local constants for OBs, FCs and FBs and global constants for the entire user program in a controller. Advantages * User constants can be used for changing constant values globally or locally for all usage locations. * With user constants, the program can be made more readable. * Local user constants are defined in the block interface. * Global user constants are defined in "PLC tags". * The user program only enables read access to the user constants. * For know-how protected blocks the user constants are not visible. Properties Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 38 2 S7-1200/S7-1500 innovations 2.13 Internal reference ID for controller and HMI tags Recommendation * Use the user constants for improved readability of the program and central changeability of ... - error codes, - CASE instructions, - conversion factors, - natural constants ... Example Copyright Siemens AG 2018 All rights reserved Figure 2-21: Local user constant of a block for CASE instructions Figure 2-22: Global user constant of a controller Note Another application case of constants is available in the following FAQ: How can you convert the unit of a tag in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/61928891 2.13 Internal reference ID for controller and HMI tags STEP 7, WinCC, Startdrive, Safety and others integrate into the joint data base of the TIA Portal engineering framework. Changes of data are automatically accepted in all the locations in the user program, independent from whether this happens in a controller, a panel or a drive. Therefore no data inconsistencies can occur. If you create a tag, the TIA Portal automatically creates a unique reference ID. The reference ID cannot be viewed or programmed by you. This procedure is internal referencing. When changing tags (address), the reference ID remains unchanged. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 39 2 S7-1200/S7-1500 innovations 2.13 Internal reference ID for controller and HMI tags In the figure below the internal reference to the data is displayed schematically. Figure 2-23: Internal reference ID for PLC and HMI PLC1 HMI1 PLC Symbol Absolute Internal PLC name address reference ID Copyright Siemens AG 2018 All rights reserved Note Internal HMI Reference ID HMI Symbol name Access mode Connection with PLC motor1 I0.0 000123 009876 motor1 <symbolic access> PLC1_HMI1 valve2 Q0.3 000138 000578 valve2 <symbolic access> PLC1_HMI1 The ID is changed by ... * renaming tag. * changing type. * deleting the tag. Advantages * You can rewire tags without changing internal relations. The communication between controller, HMI and drive also remains unchanged. * The length of the symbolic name does not have an influence on the communication load between controller and HMI. Properties If you change the addresses of PLC tags, you only have to reload the controller since the system also addresses the system internally with the reference IDs. It is not necessary to reload the HMI devices (see Figure 2-24: Changing address or adding row). Figure 2-24: Changing address or adding row PLC tags motor1 %I0.0 Changing address & PLC motor1 %I2.0 DB Elements Adding row & PLC Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 40 2 S7-1200/S7-1500 innovations 2.14 STOP mode in the event of errors 2.14 STOP mode in the event of errors In comparison to S7-300/400 there are fewer criteria with the S7-1200/1500 that lead to the "STOP" mode. Due to the changed consistency check in the TIA Portal, the "STOP" mode for S71200/1500 controllers can already be excluded in advance in most cases. The consistency of program blocks is already checked when compiling in the TIA Portal. This approach makes the S7-1200/1500 controllers more "fault tolerant" to errors than their predecessors. Advantages There are only three fault situations that put the S7-1200/1500 controllers into the STOP mode. This makes the programming of the error management clearer and easier. Properties Table 2-18: Response to errors of S7-1200/1500 Copyright Siemens AG 2018 All rights reserved Error S7-1200 S7-1500 1. Cycle monitoring time exceeded once RUN STOP (when OB80 is not configured) 2. Cycle monitoring time exceeded twice STOP STOP 3. Programming error RUN STOP (when OB121 is not configured) Error OBs: * OB80 "Time error interrupt" is called by the operating system when the maximum cycle time of the controller is exceeded. * OB121 "Programming error" is called by the operating system when an error occurs during program execution. For every error, in addition, an entry is automatically created in the diagnostic buffer. Note For S7-1200/1500 controllers there are other programmable error OBs (diagnostic error, module rack failure, etc.). More information on error responses of S7-1200/1500 can be found in the online help of the TIA Portal under "Events and OBs". Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 41 3 General programming 3.1 Operating system and user program 3 General programming 3.1 Operating system and user program SIMATIC controllers consist of operating system and user program. * The operating system organizes all functions and sequences of the controller that are not connected with a specific control task (e.g. handling of restart, updating of process image, calling the user program, error handling, memory management, etc.). The operating system is an integral part of the controller. * The user program includes all blocks that are required for the processing of your specific automation task. The user program is programmed with program blocks and loaded onto the controller. Figure 3-1: Operating system and user program User program FB FC Local Copyright Siemens AG 2018 All rights reserved Hardware Operating system OB Main cyclic call FC FC Global For SIMATIC controllers the user program is always executed cyclically. The "Main" cycle OP already exists in the "Program blocks" folder after a controller was created in STEP 7. The block is processed by the controller and recalled in an infinite loop. 3.2 Program blocks In STEP 7 (TIA Portal) there are all familiar block types from the previous STEP 7 versions: * Organization blocks * Function blocks * Functions * Data blocks Experienced STEP 7 users will know their way around straight away and new users can very easily get familiar with the programming. Advantages * You can give your program a good and clear structure with the different block types. * Due to a good and structured program you get many function units that can be multiply reused within a project and also in other projects. These function units then usually only differ by a different configuration (see chapter 3.2.9 Reusability of blocks). Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 42 3 General programming 3.2 Program blocks * You project or your plant becomes more transparent. This is to say, error states in a plant can be more easily detected, analyzed and removed. In other words, the maintainability of your plant becomes easier. This is also the case for errors in programming. Recommendation * Structure your automation task. * Divide the entire function of your plant into individual areas and form subfunction units. Divide these function units again into smaller units and functions. Divide until you get functions that you can use several times with different parameters. * Specify the interfaces between the function units. Define the unique interfaces for functionalities that are to be delivered by "external companies". All organization blocks, function blocks and functions can be programmed with the following languages: Table 3-1: Programming languages Copyright Siemens AG 2018 All rights reserved Programming language 3.2.1 S7-1200 S7-1500 Ladder diagram (LAD) yes yes Function block diagram (FBD) yes yes Structured Control Language (SCL) yes yes Graph no yes Statement list (STL) no yes Organization blocks (OB) Figure 3-2: "Add new block" dialog (OB) OBs are the interface between the operating system and the user program. They are called by the operating system and control, for example, the following processes: * Startup behavior of the controller * Cyclic program processing * Interrupt-controlled program processing * Error handling Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 43 3 General programming 3.2 Program blocks Depending on the controller a number of different OB types are available. Properties * OBs are called by the operating system of the controller. * Several Main OBs can be created in a program. The OBs are processed sequentially by OB number. Figure 3-3: Using several Main OBs User program Main1 OB1 MainX OB200 Copyright Siemens AG 2018 All rights reserved MainY OB300 FB FC Local FB FC Local FB FC Local Recommendation * Encapsulate the different program parts which should maybe be replaceable from controller to controller, into several Main OBs. * Avoid the communication between the different Main OBs. They can then be used independent of each other. If you nevertheless exchange data between the individual main OBs, use the global DBs (see chapter 4.2 No bit memory but global data blocks). * Divide all program parts that belong to each other into folders and store them for reusability in the project or global library. Figure 3-4: Storing program parts in order in the project library Further information is available in chapter 3.7 Libraries. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 44 3 General programming 3.2 Program blocks Note More information can be found in the following entry: Which organization blocks can be used in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/40654862 3.2.2 Functions (FC) Copyright Siemens AG 2018 All rights reserved Figure 3-5: "Add new block" dialog (FC) FCs are blocks without cyclic data storages. This is why the values of block parameters cannot be saved until the next call and have to be provided with actual parameters when called. Properties * FCs are blocks without cyclic data storages. * Temporary tags are undefined when called in non-optimized blocks. In optimized blocks, the values are always preset with the default value (S7-1500 and S7-1200 firmware V4 and higher). Thus, the resulting behavior is not accidental but reproducible behavior. * In order to permanently save the data of an FC, the functions of the global data blocks are available. * FCs can have several outputs. * The function value can be directly reused in SCL in a formula. Recommendation * Use the functions for frequently recurring applications that are called several times in different locations of the user program. * Use the option to directly reuse the function value in SCL. <Operand> := <FC name> (Parameter list); Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 45 3 General programming 3.2 Program blocks Example In the following example a mathematical formula is programmed in a FC. The result of the calculation is directly declared as return value and the function value can be directly reused. Table 3-2: Reusing function value Copyright Siemens AG 2018 All rights reserved Step Note Instruction 1. Create an FC with the mathematical formula (circular segment) and define the "return" value as the result for the formula. 2. Call the FC with the circular segment calculation in any block (SCL). <Operand> := <FC name> (parameter list); More information can be found in the following entries: What is the maximum number of parameters you are allowed to define in STEP 7 (TIA Portal) for a function in the S7-1200/S7-1500 CPU? https://support.industry.siemens.com/cs/ww/en/view/99412890 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 46 3 General programming 3.2 Program blocks 3.2.3 Function blocks (FB) Figure 3-6: "Add new block" dialog (FB) Copyright Siemens AG 2018 All rights reserved FBs are blocks with cyclic data storage, in which values are permanently stored. The cyclic data storage is realized in an instance DB. Figure 3-7: Calling a function block Instance DB Call of a function block in the block editor Properties * FBs are blocks with cyclic data storage. * Temporary tags are undefined when called in non-optimized blocks. In optimized blocks, the values are always preset with the default value (S7-1500 and S7-1200 firmware V4). Thus, the resulting behavior is not accidental but reproducible. * Static tags keep the value from cycle to cycle Recommendation * Use the function blocks in order to create subprograms and structure the user program. A function block can also be called several times in different locations of the user program. This makes programming of frequently recurring program parts easier. * If function blocks are applied multiply in the user program, use separate instances, preferably multi-instances. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 47 3 General programming 3.2 Program blocks 3.2.4 Instances The call of a function block is called instance. The data with which the instance is working is saved in an instance DB. Instance DBs are always created according to the specifications in the FB interface and can therefore not be changed in the instance DB. Figure 3-8: Structure of the interfaces of an FB Instance Input Output InOut Copyright Siemens AG 2018 All rights reserved Static The instance DB consists of a permanent memory with the interfaces input, output, InOut and static. Temporary tags are stored in a volatile memory (L stack). The L stack is always only valid for the current processing. I.e. temporary tags have to be initialized in each cycle. Properties * Instance DBs are always assigned to a FB. * Instance DBs do not have to be created manually in the TIA Portal and are created automatically when calling an FB. * The structure of the instance DB is specified in the appropriate FB and can only be changed there. Recommendation * Program it in a way so that the data of the instance DB can only be changed by the appropriate FB. This is how you can guarantee that the block can be used universally in all kinds of projects. For more information, please refer to chapter 3.4.1 Block interfaces as data exchange. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 48 3 General programming 3.2 Program blocks 3.2.5 Multi-instances With multi-instances called function blocks can store their data in the instance data block of the called function block. This means, if another function block is called in a function block, it saves its data in the instance DB of the higher-level FBs. The functionality of the called block is thus maintained even when the calling block is transferred. The following figure shows an FB that uses another FB ("IEC Timer"). All data is saved in a multi instance DB. It is thus possible to create a block with an independent time behavior, for example, a clock generator. Figure 3-9: Multi-instances FB Multi-instance DB FB Parameters Switch-off delay call Copyright Siemens AG 2018 All rights reserved FB-Statics TOF_TIME Advantages * Reusability * Multiple calls are possible * Clearer program with fewer instance DBs * Simple copying of programs * Good options for structuring during programming * Multi-instances are memory areas within instance DBs. Properties Recommendation Use multi-instances in order to ... * reduce the number of instance DBs. * create reusable and clear user programs. * program local functions, for example, timer, counter, edge evaluation. Example If you require the time and counter function, use the "IEC Timer" blocks and the "IEC Counter" blocks instead of the absolutely addressed SIMATIC Timer. If possible, also always use multi-instances here. Thus, the number of blocks in the user program is kept low. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 49 3 General programming 3.2 Program blocks Copyright Siemens AG 2018 All rights reserved Figure 3-10: Library of the IEC Timer Note More information can be found in the following entries: How do you declare the timers and counters for the S7-1500 in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/67585220 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 50 3 General programming 3.2 Program blocks 3.2.6 Transferring instance as parameters (V14) Instances of called blocks can be defined as InOut parameters. Advantages * It is possible to create standardized functions whose dynamic instances are transferred. * Only when calling the block it is specified what instance is used. Example Copyright Siemens AG 2018 All rights reserved Figure 3-11: Transferring instance as parameter Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 51 3 General programming 3.2 Program blocks 3.2.7 Global data blocks (DB) Figure 3-12: "Add new block" dialog (DB) Variable data is located in data blocks that are available to the entire user program. Copyright Siemens AG 2018 All rights reserved Figure 3-13: Global DB as central data memory FC OB DB FB Local Advantages * Well-structured memory area * High access speed * All blocks in the user program can access global DBs. * The structure of the global DBs can be arbitrarily made up of all data types. * Global DBs are either created via the program editor or according to a previously created "user-defined PLC data type" (see chapter 3.6.4 STRUCT data type and PLC data types). * A maximum of 256 structured tags (ARRAY, STRUCT) can be defined. This does not apply to tags that are derived from a PLC-data type. Properties Recommendation * Use the global DBs when data is used in different program parts or blocks. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 52 3 General programming 3.2 Program blocks Note More information can be found in the following entry: How is the declaration table for global data blocks structured in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/68015630 3.2.8 Downloading without reinitialisation In order to change user programs that already run in a controller, S7-1200 (firmware V4.0) and S7-1500 controllers offer the option to expand the interfaces of optimized function or data blocks during operation. You can load the changed blocks without setting the controller to STOP and without influencing the actual values of already loaded tags. Figure 3-14: Load without reinitialization Block in project Block in controller Copyright Siemens AG 2018 All rights reserved Name Wert 1 Block in controller Name Name variable1 variable1 3.4 variable2 451 variable3 23 variable4 variable4 0 variable5 variable5 0 variable1 3.4 variable2 451 variable2 variable3 23 variable3 3 Wert 2 Execute the following steps whilst the controller is in RUN mode. 1. Enable "Downloading without reinitialisation" 2. Insert newly defined tags in existing block 3. Load block into controller Advantages * Reloading of newly defined tags without interrupting the running process. The controller stays in "RUN" mode. * Downloading without reinitiatialization is only possible for optimized blocks. * The newly defined tags are initialized. The existing tags keep their current value. * A block with reserve requires more memory space in the controller. * The memory reserve depends on the work memory of the controller; however, it is max. 2 MB. * It is assumed that a memory reserve has been defined for block. * By default, the memory reserve is set to 100 byte. * The memory reserve is defined individually for every block. * The blocks can be variably expanded. Properties Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 53 3 General programming 3.2 Program blocks Recommendation * Define a memory reserve for blocks that are to be expanded during commissioning (e.g. test blocks). The commissioning process is not disturbed by a download since the actual values of the existing tags remain. Example: Stetting memory reserve on the block The following table describes how you can set the memory reserve for the downloading without reinitializing. Table 3-3: Setting memory reserve Step Right-click any optimized block in the project tree and select "Properties". Copyright Siemens AG 2018 All rights reserved 1. Instruction Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 54 3 General programming 3.2 Program blocks Step Instruction 2. Click "Download without reinitialization". 3. Enter the desired memory reserve for "Memory reserve". 4. Confirm with "OK". Copyright Siemens AG 2018 All rights reserved Note You can also set a default value for the size of the memory reserve for new blocks in the TIA portal. In the menu bar, navigate to "Options - Settings" and then to "PLC programming - General - Download without reinitialization". Example: Downloading without reinitialisation The following example displays how to download without reinitialization. Table 3-4 Load without reinitialization Step Instruction 1. Prerequisite: a memory reserve has to be set (see above) 2. Open, e.g. an optimized global DB. 3. Click the "Activate memory reserve" button and confirm the dialog with "OK". Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 55 3 General programming 3.2 Program blocks Copyright Siemens AG 2018 All rights reserved Step Note Instruction 4. Add a new tag (retentive tags are also possible). 5. Download the block to the controller. 6. Result: * Actual values of the block remain Further information can be found in the online help of the TIA Portal under "Loading block extensions without reinitialization". For further information, refer to the following entry: How is the declaration table for global data blocks structured in STEP 7-1500 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/68015630 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 56 3 General programming 3.2 Program blocks 3.2.9 Reusability of blocks The block concept offers you a number of options to program in a structured and effective way. Advantages * Blocks can be used universally in any location of the user program. * Blocks can be used universally in different projects. * When every block receives an independent task, a clear and well-structured user program is automatically created. * There are clearly fewer sources of errors. * Simple error diagnostic possible. Recommendation Copyright Siemens AG 2018 All rights reserved If you want to reuse the block, please note the following recommendations: * Always look at blocks as encapsulated functions. I.e. each block represents a completed partial task within the entire user program. * Use several cyclic Main OBs to group the plant parts. * Always execute a data exchange between the blocks via its interfaces and not via its instances (chapter 3.4.1 Block interfaces as data exchange). * Do not use project-specific data and avoid the following block contents: * - Access to global DBs and use of single-instance DBs - Access to tags - Access to global constants Reusable blocks have the same requirements as know-how-protected blocks in libraries. This is why you have to check the blocks for reusability based on the "Multiple instance capability" block property. Compile the block before the check. Figure 3-15: Block attributes Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 57 3 General programming 3.2 Program blocks 3.2.10 Auto numbering of blocks For internal processing, required block numbers are automatically assigned by the system (setting in the block properties). Figure 3-16: Auto numbering of blocks Copyright Siemens AG 2018 All rights reserved Copy and paste confict with same block number System solves the conflict with compiling the project. Block gets next free number autmatically. Advantages * Conflicting block numbers, e.g. as a result of copying, automatically deletes the TIA Portal during compilation. Recommendation * Leave the existing setting "Automatic" unchanged. Figure 3-17: Setting in the block Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 58 3 General programming 3.3 Block interface types 3.3 Block interface types FBs and FCs have three different interface types: In, InOut and Out. Via these interface types the blocks are provided with parameters. The parameters are processed and output again in the block. InOut parameters serve for the transfer of data to the called block as well as the return of results. There are two different options for the parameter transfer of data. 3.3.1 Call-by-value When calling the block, the value of the actual parameter is copied onto the formal parameter of the block. For this, an additional memory in the called block is provided. Figure 3-18: Transfer of the value Copyright Siemens AG 2018 All rights reserved myInt" value: 31 FC / FB in1 value: 31 Properties 3.3.2 IN * Each block displays the same behavior as the transferred parameters Wert: '2' * Values are copied when calling the block Call-by-reference When calling the block, a reference is transferred to the address of the actual parameter. For this, no additional memory is required. Figure 3-19: Referencing the actual parameter (pointer to data storage of the parameter) myString" velue: 'test' FC / FB inOut1 Reference to myString" Properties * Each block displays the same behavior as the referenced parameters. * Actual parameters are referenced when the block is called, i.e. with the access, the values of the actual parameter are directly read or written. Recommendation * Generally use the InOut interface type for structured tags (e.g. of the ARRAY, STRUCT, STRING, type...) in order to avoid enlarging the required data memory unnecessarily. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 59 3 General programming 3.4 Memory concept 3.3.3 Overview for transfer of parameters The following table gives a summarized overview of how S7-1200/1500 block parameters with elementary or structured data types are transferred. Table 3-5: Overview for transfer of parameters Block type / formal parameter FC FB Copyright Siemens AG 2018 All rights reserved Note Elementary data type Structured data type Input Copy Reference Output Copy Reference InOut Copy Reference Input Copy Copy Output Copy Copy InOut Copy Reference When optimized data with the property "non-optimized access" is transferred when calling the block, it is generally transferred as copy. When the block contains many structured parameters this can quickly lead to the temporary storage area (local data stack) of the block to overflow. This can be avoided by setting the same access type for both blocks (chapter 2.6.5 Parameter transfer between blocks with optimized and non-optimized access). 3.4 Memory concept For STEP 7 there is generally the difference between the global and local memory area. The global memory area is available for each block in the user program. The local memory area is only available within the respective block. 3.4.1 Block interfaces as data exchange If you are encapsulating the functions and program the data exchange between the blocks only via the interfaces, you will clearly have advantages. Advantages * Program can be made up modularly from ready blocks with partial tasks. * Program is easy to expand and maintain. * Program code is easier to read and test since there are no hidden cross accesses. Recommendation * If possible, only use local tags. Thus, you can use the blocks universally and in a modular fashion. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 60 3 General programming 3.4 Memory concept * Use the data exchange via the block interfaces (In, Out, InOut), his guarantees the reusability of the blocks. * Only use the instance data blocks as local memory for the respective function block. Other blocks should not be written into instance data blocks. Figure 3-20: Avoiding access to instance data blocks FB Local OB FC FB Local If only the block interfaces are used for the data exchange it can be ensured that all blocks can be used independent from each other. Copyright Siemens AG 2018 All rights reserved Figure 3-21: Block interfaces for data exchange OB FC FB Local FB Local 3.4.2 Global memory Memories are called global when they can be accessed from any location of the user program. There are hardware-dependent memories (for example, bit memory, times, counters, etc.) and global DBs. For hardware-dependent memory areas there is the danger that the program may not be portable to any controller because the areas there may already be used. This is why you should use global DBs instead of hardware-dependent memory areas. Advantages * User programs can be used universally and independent from the hardware. * The user program can be modularly configured without having to divide bit memory areas for different users. * Optimized global DBs are clearly more powerful than the bit memory address area that is not optimized for reasons of compatibility. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 61 3 General programming 3.4 Memory concept Recommendation * Do not use any bit memory and use global DBs instead. * Avoid hardware-dependent memory, such as, for example, clock memory or counter. Use the IEC counter and timer in connection with multi-instances instead (chapter 3.2.5 Multi-instances). The IEC timers can be found in "Instructions - Basic Instructions - Timer operations". Figure 3-22: IEC timers Copyright Siemens AG 2018 All rights reserved 3.4.3 Local memory * Static tags * Temporary tags Recommendation Note * Use the static tags if the values are required in the next cycle. * Use the temporary tags as intermediate memory in the current cycle. The access time for temporary tags is shorter than for static ones. * If an Input/Output tags is accessed very frequently, use a temporary tag as intermediate memory to save runtime. Optimized blocks: Temporary tags are initialized in each block call with the default value (S7-1500 / S7-1200 firmware V4 or higher). Non-optimized blocks: Temporary tags are undefined for each call of the block. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 62 3 General programming 3.4 Memory concept 3.4.4 Access speed of memory areas STEP 7 offers different options of memory access. For system-related reasons there are faster and slower accesses to different memory areas. Figure 3-23: Different memory access Access speed Non-structured elementary data type FC parameter fast intermediate 1 Retain tags Non-retain tags slow 2 Tags [PLC data type] 1 Temporary tags 1 1 Copyright Siemens AG 2018 All rights reserved Indexed accesses with runtime tindex 4 5 Accesses to checks for at runtime require (register, indirect and indirect DB accesses) 5 5 6 Copying between optimized and non-optimized blocks 3 2 Access to optimized DBs Access to non-optimized blocks Fastest access in the S7-1200/1500 in descending order 1. Optimized blocks: Temporary tags, parameters of an FC and FB, non-retentive static tags, tags [PLC data type] 2. Optimized blocks whose access for compiling is known: - Retentive FB tags - Optimized global DBs 3. Access to non-optimized blocks 4. Indexed accesses with index that was calculated at runtime (e.g. Motor [i]) 5. Accesses that require checks at runtime - Accesses to DBs that are created at runtime or which were opened indirectly (e.g. OPN DB[i]) - Register access or indirect memory access 6. Copying of structures between optimized and non-optimized blocks (apart from Array of Bytes) Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 63 3 General programming 3.5 Retentivity 3.5 Retentivity In the event of a failure of the power supply, the controller copies the retentive data with its buffer energy from the controller's work memory to a non-volatile memory. After restarting the controller, the program processing is resumed with the retentive data. Depending on the controller, the data volume for retentivity has different sizes. Table 3-6: Retentive memory for S7-1200/1500 Usable retentive memory for bit memory, times, counters, DBs and technology objects Controller CPU 1211C,1212C, 1214C, 1215C, 1217C 10 kByte CPU 1511-1 PN 88 kByte CPU 1513-1 PN 88 kByte CPU 1515-2 PN, CPU 1516-3 PN/DP 472 kByte CPU 1518-4 PN/DP 768 kByte Copyright Siemens AG 2018 All rights reserved Table 3-7: Differences of S7-1200 and S7-1500 S7-1200 Retentivity can only be set for bit memory S7-1500 Retentivity can be set for bit memory, times and counters Advantages * Retentive data maintains its value when the controller goes to STOP and back to RUN or in the event of power failure and a restart of the controller. Properties For elementary tags of an optimized DB the retentivity can be set separately. Nonoptimized data blocks can only be defined completely retentive or non-retentive. Retentive data can be deleted with the actions "memory reset" or "Reset to factory settings" via: * Operating switch on the controller (MRES) * Display of the controller * Online via STEP 7 (TIA Portal) Recommendation * Do not use the setting "Set in IDB". Always set the retentive data in the function block and not in the instance data block. The "Set in IDB" setting increases the processing time of the program sequence. Always either select "Non-retain" or "Retain" for the interfaces in the FB. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 64 3 General programming 3.5 Retentivity Figure 3-24: Program editor (Functions block interfaces) Copyright Siemens AG 2018 All rights reserved Figure 3-25: Program editor (data block) Example: Retentive PLC tags The setting of the retentive data is performed in the tables of the PLC tags, function blocks and data blocks. Figure 3-26: Setting of the retentive tags in the table of PLC tags Retentivity can be set from address 0 onward! e.g. from MB0, T0 or C0 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 65 3 General programming 3.5 Retentivity Example: Retentive counter You can also declare instances of functions (timer, counter, etc.) retentive. As already described in chapter 3.2.5 Multi-instances, you should always program such functions as multi-instance. Copyright Siemens AG 2018 All rights reserved Figure 3-27: Retentive counter as multi-instance Note If the retentive memory on the PLC is not sufficient, it is possible to store data in the form of data blocks that are only located in the load memory of the PLC. The N following entry is described by taking the example of an S7-1200. This o programming also works for S7-1500. t eMore information can be found in the following entries: How do you configure data blocks in STEP 7 (TIA Portal) with the "Only store in load memory" attribute for a S7-1200? https://support.industry.siemens.com/cs/ww/en/view/53034113 Using Recipe Functions for persistent Data with SIMATIC S7-1200 and S7-1500 https://support.industry.siemens.com/cs/ww/en/view/109479727 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 66 3 General programming 3.6 Symbolic addressing 3.6 Symbolic addressing 3.6.1 Symbolic instead of absolute addressing The TIA Portal is optimized for symbolic programming. This results in many advantages. Due to symbolic addressing, you can program without having to pay attention to the internal data storage. The controller handles where the best possible storage is for the data. You can therefore completely concentrate on the solution for your application task. Copyright Siemens AG 2018 All rights reserved Advantages * Easier to read programs through symbolic tag names * Automatic update of tag names at all usage locations in the user program * Memory storage of the program data does not have to be manually managed (absolute addressing) * Powerful data access * No manual optimization for performance or program size reasons required * Auto-complete for fast symbol input * Fewer program errors due to type safety (validity of data types is checked for all accesses) Recommendation * "Don't worry about the storage of the data" * "Think" symbolically. Enter the "descriptive" name for each function, tag or data, such as, for example, Pump_boiler_1, heater_room_4, etc. Thus a created program can be simply read, without requiring many comments. * Give all the tags used a direct symbolic name and define them afterwards with a right-click. Example Table 3-8: Example for creating symbolic tags Step Instruction 1. Open the program editor and open any block. 2. Enter a symbolic name directly at the input of an instruction. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 67 3 General programming 3.6 Symbolic addressing Copyright Siemens AG 2018 All rights reserved Step Instruction 3. Right-click next to the block and select "Define tag..." in the context menu. 4. Define the tag. There is an elegant method to save time, if you want to define several tags in a network. First of all, assign all tag names. Then define all tags at the same time with the dialog of step 4. Note More information can be found in the following entry: What are the advantages of using symbolic addressing for S7-1500 in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/67598995 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 68 3 General programming 3.6 Symbolic addressing 3.6.2 ARRAY data type and indirect field accesses The ARRAY data type represents a data structure which is made up of several elements of a data type. The ARRAY data type is suitable, for example, for the storage of recipes, material tracking in a queue, cyclic process acquisition, protocols, etc. Figure 3-28: ARRAY with 10 elements of the Integer (INT) data type Copyright Siemens AG 2018 All rights reserved You can indirectly access individual elements in the ARRAY with an index (array ["index"]). Figure 3-29: Indirect field access KOP / FUP: SCL: Advantages * Easy access through ARRAY index * No complicated pointer creation required * Fast creation and expansion possible * Useable in all programming languages * Structured data type * Data structure made of fixed number of elements of the same data type * ARRAYs can also be created multi-dimensional * Possible indirect access with runtime tag with dynamic index calculation at runtime Properties Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 69 3 General programming 3.6 Symbolic addressing Recommendation Note * Use ARRAY for indexed accesses instead of pointer (e.g. ANY pointer). This makes it easier to read the program since an ARRAY is more meaningful with a symbolic name than a pointer in a memory area. * As run tag use the DINT data type as temporary tag for highest performance. * Use the "MOVE_BLK" instruction to copy parts of an ARRAY into another one. * Use the "GET_ERR_ID" instruction to catch access errors within the Array. More information can be found in the following entries: How do you implement an array access with an S7-1500 with variable index? https://support.industry.siemens.com/cs/ww/en/view/67598676 How do you address securely and indirectly in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/97552147 Copyright Siemens AG 2018 All rights reserved In STEP 7 (TIA Portal), how do you transfer S7-1500 data between two tags of the data types "Array of Bool" and "Word"? https://support.industry.siemens.com/cs/ww/en/view/108999241 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 70 3 General programming 3.6 Symbolic addressing 3.6.3 Formal parameter Array [*] (V14 or higher) With the formal parameter Array [*], arrays with variable length can be transferred to functions and function blocks. With the instructions "LOWER_BOUND" and "UPPER_BOUND" the array limits can be determined. Advantages * Blocks that can process the flexible arrays with different lengths * Optimum readability due to fully-symbolic programming * No pointer programming for arrays of different lengths necessary anymore Example Copyright Siemens AG 2018 All rights reserved Figure 3-30:Initializing different arrays Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 71 3 General programming 3.6 Symbolic addressing 3.6.4 STRUCT data type and PLC data types The STRUCT data type represents a data structure which is made up of elements of different data types. The declaration of a structure is performed in the respective block. Figure 3-31: Structure with elements with different data types Copyright Siemens AG 2018 All rights reserved In comparison to structures, PLC data types are defined across the controller in the TIA Portal and can be centrally changed. All usage locations are automatically updated. PLC data types are declared in the "PLC data types" folder in the project navigation before being used. Figure 3-32: PLC data types Advantages * A change in a PLC data type is automatically updated in all usage locations in the user program. * Simple data exchange via block interfaces between several blocks * In PLC data types STRING tags with defined length can be declared (e.g., String[20]). As of TIA V14 a global constant can also be used for the length (e.g., String[LENGTH]). If a STRING tag is declared without defined length, the tag has the maximum length of 255 characters. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 72 3 General programming 3.6 Symbolic addressing Properties * PLC data types always end at WORD limits (see the figures below). * Please consider this system property when ... - using structures in I/O areas (see chapter 3.6.5 Access to I/O areas with PLC data types). - using frames with PLC data types for communication. - using parameter records with PLC data types for I/O. - using non-optimized blocks and absolute addressing. Figure 3-33: PLC data types always end at WORD limits PLC data type elements varByte0 1. WORD typeCustom Copyright Siemens AG 2018 All rights reserved Defined size 3 Bytes varByte1 varByte2 2. WORD ! Acutal size 4 Bytes ... Figure 3-34: PLC data types on I/O areas PLC data type I/O area 3 Bytes Tag of PLC data type Defined size 3 Bytes Acutal size 4 Bytes Recommendation * Use the PLC data types to summarize several associated data, such as, e.g. frames or motor data (setpoint, speed, rotational direction, temperature, etc.) Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 73 3 General programming 3.6 Symbolic addressing Note * Always use PLC data types instead of structures for the multiple uses in the user program. * Use the PLC data types for structuring into data blocks. * Use the PLC data types in order to specify a structure for a data block. The PLC data type can be used for any number of DBs. You can easily and conveniently create any number of DBs of the same structure and adjust them centrally on the PLC data type. More information can be found in the following entries: Libraries with PLC data types (LPD) for STEP 7 (TIA Portal) and S7-1200 / S71500 https://support.industry.siemens.com/cs/ww/en/view/109482396 How do you initialize structures into optimized memory areas for the S7-1500 STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/78678760 Copyright Siemens AG 2018 All rights reserved How do you create a PLC data type for an S7-1500 controller? https://support.industry.siemens.com/cs/ww/en/view/67599090 In STEP 7 (TIA Portal), how do you apply your own data types (UDT)? https://support.industry.siemens.com/cs/ww/en/view/67582844 Why should whole structures instead of many single components be transferred for the S7-1500 when a block is called? https://support.industry.siemens.com/cs/ww/en/view/67585079 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 74 3 General programming 3.6 Symbolic addressing 3.6.5 Access to I/O areas with PLC data types With S7-1500 controllers, you can create PLC data types and use them for structured and symbolic access to inputs and outputs. Figure 3-35: Access to I/O areas with PLC data types 1 PLC data type PLC tag 2 FB call FB interface 3 Copyright Siemens AG 2018 All rights reserved 4 7. PLC data type with all required data 8. PLC tag of the type of the created PLC data type and start address of the I/O data area (%Ix.0 or %Qx.0, e.g., %I0.0, %Q12.0, ...) 9. Transfer of the PLC tag as actual parameter to the function block 10. Output of the function block is of the type of the created PLC data type Advantages * High programming efficiency * Easy multiple usability thanks to PLC data types Recommendation * Note Use PLC data types for access to I/O areas, for example, to symbolically receive and send drive telegrams. Individual elements of a PLC data type of a tag can also be directly accessed in the user program: Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 75 3 General programming 3.6 Symbolic addressing 3.6.6 Slice access For S7-1200/1500 controllers, you can access the memory area of tags of the Byte, Word, DWord or LWord data type. The division of a memory area (e.g. byte or word) into a smaller memory area (e.g. Bool) is also called slice. The figure below displays the symbolic bit, byte and word accesses to the operands. Figure 3-36:Symbolic bit, byte, word, DWord slice access myByteVariable" BYTE Operands in Blocks, DBs und I/O/M myWordVariable" myDoubleWordVariable" my_DoubleWordVariable.%W1" myWordVariable.%X0" X 63 B7 Copyright Siemens AG 2018 All rights reserved DWORD LWORD myLongWordVariable" Examples Slice access: myLongWordVariable.%D1" WORD B1 W3 W1 D1 W0 D0 X X X 2 1 0 Bit by bit B0 Byte by byte Word by word Dword by DWord Advantages * High programming efficiency * No additional definition in the tag declaration required * Easy access (e.g. control bits) Recommendation * Note Use the slice access via AT construct rather than accessing certain data areas in operands. More information can be found in the following entry: How in STEP 7 (TIA Portal) can you access the unstructured data types bit-bybit, byte-by-byte or word-by-word and symbolically? https://support.industry.siemens.com/cs/ww/en/view/57374718 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 76 3 General programming 3.6 Symbolic addressing 3.6.7 SCL networks in LAD and FBD (V14 and higher) With SCL networks you can make calculations in LAD and FBD that can only be programmed with considerable effort in LAD and FBD instructions. Copyright Siemens AG 2018 All rights reserved Figure 3-37: Inserting SCL network Advantages * Time saving through efficient programming * Clear code, thanks to symbolic programming * Supports all SCL instructions * Supports comments Properties Recommendation * Use the SCL networks in LAD and FBD for mathematical calculations instead of instructions, such as ADD, SUBB etc. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 77 3 General programming 3.7 Libraries 3.7 Libraries With the TIA Portal you can establish independent libraries from different project elements that can be easily reused. Advantages Copyright Siemens AG 2018 All rights reserved * Simple storage for the data configured in the TIA Portal: - Complete devices (controller, HMI, drive, etc.) - Blocks, tag tables, PLC data types, watch tables, etc. - HMI screens, HMI tags, scripts, etc. * Cross-project exchange via libraries * Central update function of library elements * Versioning of library elements * Fewer error sources when using control blocks through system-supported consideration of dependencies Recommendations Note * Create the master copies for easy reusability of blocks, hardware configurations, HMI screens, etc. * Create the types for the system-supported reusability of library elements: - Versioning of blocks - Central update function of all usage locations * Use the global library for the exchange with other users or as central storage for the simultaneous use of several users. * Configure the storage location of your global library so it can automatically be opened when starting the TIA Portal. Further information is available at: https://support.industry.siemens.com/cs/ww/en/view/100451450 More information can be found in the following entries: Which elements of STEP 7 (TIA Portal) and WinCC (TIA Portal) can you store in a library as Type or as Master Copy? https://support.industry.siemens.com/cs/ww/en/view/109476862 How can you open a global library with write access rights in STEP 7 (TIA Portal)? https://support.industry.siemens.com/cs/ww/en/view/37364723 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 78 3 General programming 3.7 Libraries 3.7.1 Types of libraries and library elements Generally there are two different types of libraries: * "Project library" * "Global library" The content consists of two storage types each: * "Types" * "Master Copies" Figure 3-38: Libraries in the TIA Portal 1 Copyright Siemens AG 2018 All rights reserved 3 4 2 (1) "Project library" - Integrated in the project and managed with the project - Allows the reusability within the project (2) "Global library" - Independent library - Use within several projects possible A library includes two different types of storage of library elements: (3) "Master copies" - Copies of configuration elements in the library (e.g. blocks, hardware, PLC tag tables, etc.) - Copies are not connected with the elements in the project. - Master copies can also be made up several configuration elements. (4) "Types" - Types are connected with your usage locations in the project. When types are changed, the usage locations in the project can be updated automatically. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 79 3 General programming 3.7 Libraries 3.7.2 - Supported types are control blocks (FCs, FBs), PLC data types, HMI screens, HMI faceplates, HMI UDT, scripts). - Subordinate elements are automatically typified. - Types are versioned: Changes can be made by creating a newer version. - There can only be one version of a used type within a controller. Type concept The type concept allows the creation of standardized automation functions that you can use in several plants or machines. The type concept supports you with versioning and updating functions. You can use types from the library in the user program. This offers the following advantages: Copyright Siemens AG 2018 All rights reserved Advantages * Central update of all usage locations in the project * Unwanted modifications of usage locations of types are not possible. * The system guarantees that types always remain consistent by hindering unwanted delete operations. * If a type is deleted, all usage locations in the user program are deleted. Properties By using types you can make the changes centrally and update them in the complete project. Figure 3-39: Typifying with user libraries Project User library Use without typification Master copy Use Use Use V2 Central update to newer version Update Typ V1 Use V2 with typification Typ V2 Use V2 * Types are always marked for better identification Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 80 3 General programming 3.7 Libraries 3.7.3 Differences between the typifiable objects for CPU and HMI There are system-related differences between the typifiable objects for controllers and HMI: Table 3-9: Differences of types for controller and HMI Controller HMI Subordinate control elements are typified. Subordinate HMI elements are not typified. Subordinate control elements are instanced. Subordinate HMI elements are not instanced. Control elements are edited in a test environment. HMI images and HMI scripts are edited in a test environment. Faceplates and HMI UDTs are directly edited in the library without test environment. Further information on the handling of libraries can be found in the following example. Copyright Siemens AG 2018 All rights reserved 3.7.4 Versioning of a block Example: Creating a type The following example shows you how the basic functions of the libraries are used with types. Table 3-10: Creating a type Step 1. Instruction Create a new PLC data type with "Add new data type" and create some tags. Later on this is the subordinate type. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 81 3 General programming 3.7 Libraries Copyright Siemens AG 2018 All rights reserved Step Instruction 2. Create a new function block with "Add new Block". This is the higher-level type. 3. Define an output tag of the data type you have created. The PLC data type is therefore subordinate to the function block. 4. Drag the function block via drag-and-drop into the "Types" folder in the project library. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 82 3 General programming 3.7 Libraries Step Instruction Optionally assign: Type name, version, author and comment and confirm the dialog with "OK". 6. The subordinate PLC data type is automatically also stored in the library. Copyright Siemens AG 2018 All rights reserved 5. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 83 3 General programming 3.7 Libraries Example: Changing a type Table 3-11: Changing a type Copyright Siemens AG 2018 All rights reserved Step Instruction 1. Right-click the block in the "Project library" and select "Edit type" 2. Select which controller is to be used as test environment and confirm the dialog with "OK". If several controllers in the project use the selected block, a controller has to be selected as test environment. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 84 3 General programming 3.7 Libraries Copyright Siemens AG 2018 All rights reserved Step Instruction 3. The block opens. A new version of the block is created. 4. Add an input tag. In this place you have the option to test the change on the block by loading the project onto a controller. When you have finished testing the block, continue with the following steps. 5. Click the "release the version" button. 6. A dialog box opens. Here you can store a version-related comment. Confirm the dialog with "OK". If there are several usage locations of the block in different controllers of the project, you can update them all at the same time: "Update instances in the project". If older versions of the element are no longer required you can delete them by clicking "Delete unused type versions from library" Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 85 3 General programming 3.8 Increased performance for hardware interrupts 3.8 Increased performance for hardware interrupts The processing of the user program can be influenced by events such as hardware interrupts. When you need a fast response of the controller to hardware events (e.g. a rising edge of a channel of a digital input module), configure a hardware interrupt. For each hardware interrupt a separate OB can be programmed. This OB is called by the operating system of the controller in the event of a hardware interrupt. The cycle of the controller is therefore interrupted and continued after processing the hardware interrupt. Figure 3-40: Hardware interrupt is calling OB Event e.g. falling edge E6.1 e.g. rising edge E0.0 Copyright Siemens AG 2018 All rights reserved Hardware interrupt OB40 Hardware interrupt_1 OBxxx In the following figure you can see the configuration of a "hardware interrupt" in the hardware configuration of a digital input module. Figure 3-41: Configuring hardware interrupt Advantages * Fast system response to events (rising, falling edge, etc.) * Each event can start a separate OB. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 86 3 General programming 3.8 Increased performance for hardware interrupts Recommendation * Use the hardware interrupts in order to program fast responses to hardware events. * If the system response is not fast enough despite programming a hardware interrupt, you can still accelerate the response. Set as small an "Input delay" as possible in the module. A response to an event can always only occur if the input delay has lapsed. The input delay is used for filtering the input signal in order to, for example, compensate faults such as contact bounce or chatter. Copyright Siemens AG 2018 All rights reserved Figure 3-42: Setting input delay Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 87 3 General programming 3.9 Additional performance recommendations 3.9 Additional performance recommendations Here you can find some general recommendations that enable faster program processing of the controller. Recommendation Note the following recommendations for programming S7-1200/1500 controllers in order to achieve a high performance: Note * LAD/FBD: Disable "evaluate ENO" for blocks. This avoids tests at runtime. * STL: Do not use registers since address and data registers are only emulated for compatibility reasons by S7-1500. More information can be found in the following entries: Copyright Siemens AG 2018 All rights reserved How do you disable the ENO enable output of an instruction? https://support.industry.siemens.com/cs/ww/en/view/67797146 How can you improve the performance in STEP 7 (TIA Portal) and in the S71200/S7-1500 CPUs? https://support.industry.siemens.com/cs/ww/en/view/37571372 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 88 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10 SCL programming language: Tips and Tricks 3.10.1 Using call templates Many instructions of the programming languages offer a call template with a list of existing formal parameters. Example Table 3-12: Easy expanding of the call template Copyright Siemens AG 2018 All rights reserved Step Instruction 1. Drag an instruction from the library into the SCL program. The editor shows the complete call template. 2. Now fill in the required parameters "CU" and "PV" and finish the entry with the "Return" button. 3. The editor automatically reduces the call template. 4. If you want to edit the complete call later on again, proceed as follows. Click into the call at any place and then click "CTRL+SHIFT+SPACE". You are now in the "Call Template" mode. The editor expands the call again. You can navigate with the "TAB" button through the parameters. 5. Note: In the "Call Template" mode the writing is in italics. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 89 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10.2 What instruction parameters are mandatory? If you are expanding the call template, the color coding will show you straight away what formal parameters of an instruction are optional and which ones are not. Mandatory parameters are marked dark. 3.10.3 Drag-and-drop with entire tag names In the SCL editor you can also use drag-and-drop functions. For tag names you are additionally supported. If you want to replace one tag by another, proceed as follows. Table 3-13: Drag-and-drop with tags in SCL Step Copyright Siemens AG 2018 All rights reserved 1. Instruction Drag the tag via drag-and-drop to the tag in the program that is to be replaced. Hold the tag for more than 1 second before releasing it. > 1 Sekunde gedruckt halten The complete tag is replaced. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 90 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10.4 Structuring with the keyword REGION (V14 or higher) The SCL code can be divided in areas with the keyword REGION. These areas can be given a name and can be collapsed and expanded. Advantages * Better overview * Easy navigation even in large blocks * Ready code fragments can be collapsed. Properties REGIONs can be nested. Recommendation Use the keyword REGION for the structuring of your SCL blocks. Example Copyright Siemens AG 2018 All rights reserved Figure 3-43: SCL editor Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 91 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10.5 Correct use of FOR, REPEAT and WHILE loops There are different versions and applications for the use of loops. The following examples show the differences. Properties: FOR loop The FOR loop runs through a defined number of runs. The loop variable is assigned a start value at the beginning. Afterwards it is incremented up to the end value in each loop run with the specified step size. For reasons of performance, the start as well as the end value is calculated once at the beginning. Consequently, the loop variable can no longer influence the loop code. Syntax FOR statCounter := statStartCount TO statEndCount DO // Statement section ; END_FOR; Copyright Siemens AG 2018 All rights reserved With the EXIT command the loop can be interrupted at any time. Properties: WHILE loop The WHILE loop is ended by a termination condition. The termination condition is checked before the start of the loop code. I.e., the loop is not executed, if the condition is not instantly fulfilled. Each variable can be adjusted for the next run in the loop code. Syntax WHILE condition DO // Statement section ; END_WHILE; Properties: REPEAT loop The REPEAT loop is ended by a termination condition. The termination condition is checked at the end of the loop code. This means the loop is run through at least once. Each variable can be adjusted for the next run in the loop code. Syntax REPEAT // Statement section ; UNTIL condition END_REPEAT; Recommendation * Use FOR loops if the loop variable is clearly defined. * Use the WHILE or REPEAT loop if a loop variable has to be adjusted during the loop processing. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 92 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10.6 Using CASE instruction efficiently With the CASE instruction in SCL, it will be exactly jumped to the selected CASE block condition. After executing the CASE block the instruction is finished. This allows you, for example, to check frequently required value ranges more specifically and easily. Example CASE #myVar OF 5: #Engine(#myParam); 10,12: #Transport(#myParam); 15: #Lift(#myParam); 0..20: #Global(#myParam); Copyright Siemens AG 2018 All rights reserved // Global is never called for the values 5, 10, 12 or 15! ELSE END_CASE; Note 3.10.7 CASE instructions also work with CHAR, STRING data types, as well as with elements (see example in chapter 2.8.5 Data type VARIANT ). No manipulation of loop counters for FOR loop FOR loops in SCL are pure counter loops, i.e. the number of iterations is fixed when the loop is entered. In a FOR loop, the loop counter cannot be changed. With the EXIT instruction a loop can be interrupted at any time. Advantages * The compiler can optimize the program better, since it does not know the number of iterations. Example FOR #statVar := #statLower TO #statUpper DO #statVar := #statVar + 1; // no effect, compiler warning END_FOR; Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 93 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10.8 FOR loop backwards In SCL you can also increment the index of FOR loops backwards or in another step width. For this, use the optional "BY" key word in the loop head. Example FOR #statVar := #statUpper TO #statLower BY -2 DO END_FOR; If you are defining "BY" as "-2", as in the example, the counter is lowered by 2 in every iteration. If you omit "BY", the default setting for "BY" is 1 3.10.9 Easy creation of instances for calls Copyright Siemens AG 2018 All rights reserved If you prefer to work with the keyboard, there is a simple possibility to create instances for blocks in SCL. Example Table 3-14: Easy creation of instances Step 3.10.10 Instruction 1. Give the block a name, followed by a "." (dot). The automatic compilation now shows you the following. 2. On the top you can see the already existing instances. In addition, you can directly create a new single instance or multi-instance. Use the shortcuts "s" or "m" to go directly to the respective entries in the automatic compilation window. Handling of time tags You can calculate the time tags in SCL just as with normal numbers i.e. you do not need to look for additional functions, such as, e.g. T_COMBINE but you can use simple arithmetic. This approach is called "overload of operands". The SCL compiler automatically uses the suitable functions. You can use a reasonable arithmetic for the time types and can therefore program more efficiently. Example time difference := time stamp_1 - time stamp_2; The following table summarizes the overloaded operators and the operations behind it: Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 94 3 General programming 3.10 SCL programming language: Tips and Tricks Copyright Siemens AG 2018 All rights reserved Table 3-15: Overloaded operands for SCL overloaded operand Operation ltime + time T_ADD LTime ltime - time T_SUB LTime ltime + lint T_ADD LTime ltime - lint T_SUB LTime time + time T_ADD Time time - time T_SUB Time time + dint T_ADD Time time - dint T_SUB Time ldt + ltime T_ADD LDT / LTime ldt - ltime T_SUB LDT / LTime ldt + time T_ADD LDT / Time ldt - time T_SUB LDT / Time dtl + ltime T_ADD DTL / LTime dtl - ltime T_SUB DTL / LTime dtl + time T_ADD DTL / Time dtl - time T_SUB DTL / Time ltod + ltime T_ADD LTOD / LTime ltod - ltime T_SUB LTOD / LTime ltod + lint T_ADD LTOD / LTime ltod - lint T_SUB LTOD / LTime ltod + time T_ADD LTOD / Time ltod - time T_SUB LTOD / Time tod + time T_ADD TOD / Time tod - time T_SUB TOD / Time tod + dint T_ADD TOD / Time tod - dint T_SUB TOD / Time dt + time T_ADD DT / Time dt - time T_SUB DT / Time ldt - ldt T_DIFF LDT dtl - dtl T_DIFF DTL dt - dt T_DIFF DT date - date T_DIFF DATE ltod - ltod T_DIFF LTOD date + ltod T_COMBINE DATE / LTOD date + tod T_COMBINE DATE / TOD Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 95 3 General programming 3.10 SCL programming language: Tips and Tricks 3.10.11 Unnecessary IF instruction Programmers often think in IF-THEN-ELSE instructions. This frequently leads to unnecessary constructs in programs. Example IF (statOn1 = TRUE AND statOn2 = TRUE) THEN statMotor := TRUE; ELSE statMotor := FALSE; END_IF Recommendation Remember that for Boolean requests a direct assignment is often more effective. The entire construct can be programmed with one line. Copyright Siemens AG 2018 All rights reserved Example statMotor := statOn1 AND statOn2; Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 96 4 Hardware-independent programming 4.1 Data types of S7-300/400 and S7-1200/1500 4 Hardware-independent programming To make sure that a block can be used on all controllers without any further adjustments, it is important not use hardware-dependent functions and properties. 4.1 Data types of S7-300/400 and S7-1200/1500 Below is a list of all elementary data types and data groups. Recommendation * Only use the data types that are supported by the controllers on which the program is to run. Table 4-1: Elementary data types correspond to standard EN 61131-3 Description S7-1200 S7-1500 * * * * BOOL BYTE WORD DWORD yes yes yes * LWORD no no yes Character type * CHAR (8 bit) yes yes yes Numerical data types * * * INT (16 bit) DINT (32 bit) REAL (32 bit) yes yes yes * * * * * SINT (8 bit) USINT (8 bit) UINT (16 bit) UDINT (32 bit) LREAL (64 bit) no yes yes * * LINT (64 bit) ULINT (64 bit) no no yes * * * TIME DATE TIME_OF_DAY yes yes yes * S5TIME yes no yes * * LTIME L_TIME_OF_DAY no no yes Bit data types Copyright Siemens AG 2018 All rights reserved S7-300/400 Time types Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 97 4 Hardware-independent programming 4.1 Data types of S7-300/400 and S7-1200/1500 Table 4-2 Data groups that are made up of other data types Description S7-300/400 S7-1200 S7-1500 * DT (DATE_AND_TIME) yes no yes * DTL no yes yes * LDT (L_DATE_AND_TIME) no no yes Character type * STRING yes yes yes Feld * ARRAY yes yes yes Structure * STRUCT yes yes yes Time types Table 4-3: Parameter types for formal parameters that are transferred between blocks Description Pointer Copyright Siemens AG 2018 All rights reserved Blocks PLC data types S7-300/400 S7-1200 S7-1500 * * POINTER ANY yes no yes 1) * VARIANT no yes yes * * TIMER COUNTER yes yes 2) yes * * BLOCK_FB BLOCK_FC yes no yes * * BLOCK_DB BLOCK_SDB yes no no * VOID yes yes yes * PLC DATA TYPE yes yes yes 1) For optimized access, only symbolic addressing is possible 2) For S7-1200/1500 the TIMER and COUNTER data type is represented by IEC_TIMER and IEC_Counter. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 98 4 Hardware-independent programming 4.2 No bit memory but global data blocks 4.2 No bit memory but global data blocks Advantages * Optimized global DBs are clearly more powerful than the bit memory address area that is not optimized only for reasons of compatibility. Recommendation * 4.3 Dealing with bit memory (system and clock flags also) is problematic since the size of the flag area of each controller has is different. Do not use bit memory for the programming but always global data blocks. This is how the program can always be used universally. Programming of "Cycle bits" Recommendation Copyright Siemens AG 2018 All rights reserved For the programming of clock memory, the hardware configuration always has to be correct. Use a programmed block as clock generator. Below, you can find a programming example for a clock generator in the SCL programming language. Example The programmed block has the following functions. A desired frequency is preset. The "Q" output is a Boolean value that toggles in the desired frequency. The "countdown" output outputs the remaining time of the current state of "q". If the desired frequency is smaller or equal 0.0, then the output q = FALSE and Countdown = 0.0. FB q [Bool] 0.5 Period duration: 2 seconds frequency [Real] countdown [Time] Note TRUE T#0S_703MS The complete programming example can be found in the following entry: https://support.industry.siemens.com/cs/ww/en/view/109479728 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 99 5 STEP 7 Safety in the TIA Portal 5.1 Introduction 5 STEP 7 Safety in the TIA Portal 5.1 Introduction TIA Portal V13 SP1 or higher are supported by fail-safe S7-1200F and S7-1500F CPUs. In these controllers, standard as well as fail-safe programming is possible in one device. For programming the fail-safe user programs, the SIMATIC STEP 7 Safety (TIA Portal) option package is used. Figure 5-1: Standard and safety program S7-1200F S7-1500F Standard user program Copyright Siemens AG 2018 All rights reserved Safety program Advantages Note * Uniform programming in standard and fail-safe program with an engineering tool: TIA Portal * Familiar programming in LAD and FBD * Uniform diagnostic and online functions Fail-safe does not mean that the program contains no errors. The programmer is responsible for the correct programming logic. Fail-safe means that the correct processing of the fail-safe user program in the controller is ensured. Note Further information on the topic of safety, such as safety requirements or the principles of safety programs can be found in: TIA Portal - An Overview of the Most Important Documents and Links - Safety https://support.industry.siemens.com/cs/ww/en/view/90939626 Applications & Tools - Safety Integrated https://support.industry.siemens.com/cs/ww/en/ps/14675/ae STEP 7 Safety (TIA Portal) - Manuals https://support.industry.siemens.com/cs/ww/en/ps/14675/man Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 100 5 STEP 7 Safety in the TIA Portal 5.2 Terms 5.2 Terms This document consistently uses the terms with the following meaning. Table 5-1: Safety terms Term Description The standard user program is the program part, which is not connected with F programming. Safety program (F program, failsafe user program) The fail-safe user program is the program part which is processed fail-safe independently of the controller. All fail-safe blocks and instructions are shaded yellow at the software user interface (e. g. in the project navigation) in order to distinguish blocks and instructions of the standard user program. The fail-safe parameters of F-CPUs and F-I/O are shaded yellow in the hardware configuration. Copyright Siemens AG 2018 All rights reserved Standard user program Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 101 5 STEP 7 Safety in the TIA Portal 5.3 Components of the safety program 5.3 Components of the safety program Das safety program always consists of user-generated, system-generated F blocks and the "Safety administration" editor. Table 5-2 Components of the safety program Description Copyright Siemens AG 2018 All rights reserved 1. "Safety administration" editor - Status of the safety program - F collective signature - Status of the safety operation - Creating/organizing F runtime groups - Information on the F blocks - Information on F-conform PLC data types - Defining/changing the access protection 2. User-created F blocks 3. System-generated F runtime blocks - Blocks contain status information on the F runtime group. 4. System-generated F-I/O data blocks - Blocks contain tags for evaluating the F modules. 5. "Compiler blocks" System-generated verification blocks - These run in the background of the controller and provide for failsafe processing of the safety program. - These blocks cannot be processed by the user. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 Screen 1 2 3 4 5 102 5 STEP 7 Safety in the TIA Portal 5.4 F-runtime group 5.4 F-runtime group A safety program is always processed in an F runtime group with defined cycle. An F runtime group consists of a "Fail-safe organization block" which calls a "Main safety block". All user-generated safety functions are called from the "Main safety block". Copyright Siemens AG 2018 All rights reserved Figure 5-2 F runtime group in the "Safety administration" editor Advantages * Runtime groups can simply be created and configured in the "Safety Administrator". * F-blocks in the runtime group are automatically created. * A maximum of two F runtime groups can be created. Properties 5.5 F signature Each F component (station, I/O, blocks) has a unique F signature. Using the F signature it can be quickly detected whether an F device configuration, F blocks or a complete station still corresponds to the original configuration or programming. Advantages * Simple and quick comparison of F blocks and F device configurations * F parameter signature (without address of F-I/O)... Properties - only changed by adjusting the parameters. - remains unchanged when changing the PROFIsafe address. However, the F collective signature of the station changes. * F block signature is only changed when the logic in the F block changes. * F block signature remains unchanged by changing the - block number, - block interface, Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 103 5 STEP 7 Safety in the TIA Portal 5.5 F signature - block version. Example Figure 5-3 Examples of F signatures 1 Copyright Siemens AG 2018 All rights reserved 2 3 1. F collective signature of the station in the "Safety administration" editor 2. F block signatures in the "Safety Administration" editor (can also be read out from the properties of the block) 3. F parameter signature in the "Device view" at "Devices & Networks" Note For S7-1500F controllers it is possible to read the F overall signature directly on the installed display or in the integrated web server. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 104 5 STEP 7 Safety in the TIA Portal 5.6 Assigning the PROFIsafe address at the F-I/O 5.6 Assigning the PROFIsafe address at the F-I/O Each F-I/O device has a PROFIsafe address for identification and communication with F controllers. When assigning the PROFIsafe address, two different configurations are possible. Table 5-3: Setting the F address ET 200M / ET 200S (PROFIsafe address type 1) ET 200MP / ET 200SP (PROFIsafe address type 2) Assigning the PROFIsafe address directly at the modules via DIL switch In the device configuration of the TIA Portal and in the DIL switch position at the periphery, the PROFIsafe address must be the same. Assigning the PROFIsafe address exclusively via TIA Portal The configured PROFIsafe address is loaded onto the intelligent coding module of the module. Copyright Siemens AG 2018 All rights reserved Advantages Note * Replacing an F module is possible without reassigning the PROFIsafe address at ET 200MP and ET 200SP. The intelligent coding module remains in the BaseUnit during module exchange. * Simple configuration since TIA Portal indicates a faulty assignment of the PROFIsafe address warnings. * The PROFIsafe addresses of all F modules can be assigned at the same time within an ET 200SP. Further information on assigning the PROFIsafe address for the F-I/O is available at: SIMATIC Industrial Software SIMATIC Safety - Configuring and Programming https://support.industry.siemens.com/cs/ww/en/view/54110126 5.7 Evaluation of F-I/O All of the current states of the respective F-I/O are saved in the F-I/O blocks. In the safety program the states can be evaluated and processed. The following differences exist between S7-1200F/1500F and S7-300F/400F. Table 5-4: Tags in the F-I/O DB with S7-300F/400F and S7-1500F Tag in F-I/O DB or value status in PAE F-I/O with S7-300/400F F-I/O with S7-1200F/1500F ACK_NEC yes yes QBAD yes yes PASS_OUT yes yes QBAD_I_xx * yes no QBAD_O_xx * yes no Value status no yes Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 105 5 STEP 7 Safety in the TIA Portal 5.8 Value status (S7-1200F/1500F) * QBAD_I_xx and QBAD_O_xx show you the validity of the channel value and correspond to the inverted value status at S7-1200F/1500F (further information is available in the following chapter). 5.8 Value status (S7-1200F/1500F) In addition to the diagnostic messages and the status and error display, the F module provides information on the validity of each input and output signal - the value status. The value status is stored in the same way as the input signal in the process image: The value status informs about the validity of the respective channel value. * 1: A valid process value is output for the channel. * 0: a substitute value is output for the channel. Copyright Siemens AG 2018 All rights reserved Table 5-5: Differences Q_BAD (S7-300F/400F) and value status (S7-1200F/1500F) Scenario QBAD (S7-300F/400F) Value status (S7-1200F/1500F) Valid values at the F-I/O (no error) FALSE TRUE Channel error occurs TRUE FALSE Channel error going (ACK_REQ) TRUE FALSE Acknowledgement of the failure (ACK_REI) FALSE TRUE Properties * The value status is entered into the process image of the inputs and outputs. * Channel value and value status of an F-I/O must only be accessed from the same F run-time group. Recommendation * For improved readability assign the ending "VS", e.g. "TagIn1VS" as the symbolic name for the value status. Example Position of the value status bits in the process image using the example of an F-DI 8x24VDC HF module. Table 5-6: Value status bits in the process image using the example of an F-DI 8x24VDC HF Byte in the FCPU Assigned bits in the F-CPU 7 6 5 4 3 2 1 0 x+0 DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0 x +1 Value status for DI7 Value status for DI6 Value status for DI5 Value status for DI4 Value status for DI3 Value status for DI2 Value status for DI1 Value status for DI0 x = module start address Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 106 5 STEP 7 Safety in the TIA Portal 5.9 Data types Note More information about the value status of all ET 200SP modules is available at: Failsafe CPUs - Manuals https://support.industry.siemens.com/cs/ww/en/ps/13719/man Failsafe I/O modules - Manuals https://support.industry.siemens.com/cs/ww/en/ps/14059/man 5.9 Data types 5.9.1 Overview There is an unrestricted scope of data types for the safety programs of the S71200/1500F. Copyright Siemens AG 2018 All rights reserved Table 5-7 Integer data types Type Size Value range BOOL 1 bit 0 .. 1 INT 16 bit -32.768 .. 32.767 WORD 16 bit -32.768 .. 65.535 DINT 32 bit -2.14 .. 2.14 Mio 32 bit T#-24d20h31m23s648ms to T#+24d20h31m23s647ms TIME 5.9.2 Implicit conversion In safety-relevant applications is may be necessary to carry out mathematical functions with tags of different data types. The function blocks necessary for this, require a defined data format of the formal parameters. It the operand does not comply with the expected data type, a conversion has to be carried out first. Under the following circumstances can the S7-1200/1500 also perform the data conversion implicitly: * IEC check is disabled. * The data types have the same length. For this reason, the following data types can be converted implicitly in the safety program: * WORD INT * DINT TIME A practical application is the addition of two time values, although the function "Add" is required as "DInt" input. The result is then also output as "Time" tag. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 107 5 STEP 7 Safety in the TIA Portal 5.9 Data types Copyright Siemens AG 2018 All rights reserved Figure 5-4: Addition of two time values Enable or disable the IEC check in the properties of the respective function block or function. Figure 5-5: Disabling IEC check Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 108 5 STEP 7 Safety in the TIA Portal 5.10 F-conform PLC data type 5.10 F-conform PLC data type For safety programs it is also possible to structure data optimal with PLC data types. Advantages * A change in a PLC data type is automatically updated in all usage locations in the user program. * F-PLC data types are declared and used in the same way as PLC data types. * As F-PLC data types, all data types which are allowed in the safety program can be used. * Nesting of F-PLC data types within other F-PLC data types is not supported. * F-PLC data types can be used in the safety program as well as in the standard user program. Copyright Siemens AG 2018 All rights reserved Properties Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 109 5 STEP 7 Safety in the TIA Portal 5.10 F-conform PLC data type Recommendation * You use F-PLC data types for accessing I/O areas (as in chapter 3.6.5 Access to I/O areas with PLC data types) * The following rules must be observed here: - The structure of the tags of the F-conform PLC data type must match the channel structure of the F-I/O. - An F-conform PLC data type for an F-I/O with 8 channels is, for example: - * 8 BOOL tags (channel value) or * 16 BOOL tags (channel value + value status) Access to F-I/O is only permitted for activated channels. When configuring a 1oo2 (2v2) evaluation, the higher channel is always deactivated. Example Figure 5-6: Access to I/O areas with F-PLC data types Copyright Siemens AG 2018 All rights reserved F-PLC data type F-I/O PLC tag Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 110 5 STEP 7 Safety in the TIA Portal 5.11 TRUE / FALSE 5.11 TRUE / FALSE The use of "TRUE" and "FALSE" signals in the safety programs can be differentiated in two application cases: * as actual parameter at blocks * as assignment to operations Actual parameter at blocks For S7-1200F/1500F controllers you can use the Boolean constants "FALSE" for 0 and "TRUE" for 1 as actual parameter for supplying formal parameters during block calls in the safety program. Only the keyword "FALSE" or "TRUE" is written to the formal parameter. Copyright Siemens AG 2018 All rights reserved Figure 5-7: "TRUE" and "FALSE" signals as actual parameter Assignments to operations In order to create "TRUE" or "FALSE" signals for operations, proceed as follows: 1. Create two static tags "statTrue" and "statFalse" of the type BOOL. 2. Assign the default value "false" to the statFalse tag. 3. Assign the default value "true" to the statTrue tag. You can use the tags as "True" and "False" read signals in the complete function block. Figure 5-8: "TRUE" and "FALSE" signals Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 111 5 STEP 7 Safety in the TIA Portal 5.12 Optimizing the compilation and program runtime 5.12 Optimizing the compilation and program runtime An important part of the safety program is the protection of the user programming by coded processing. The aim is to discover any kind of data corruption in the safety program and therefore to prevent unsafe conditions. This protection program is created during the compilation and therefore prolongs the compilation time. The runtime of the F-CPU is also prolonged through the protection program, since the F-CPU processes it additionally and compares the results with the user program. The protection program that is generated automatically by the system can be found in the system block folder of your F-CPU. Example Figure 5-9: User and system created F blocks System created F-blocks Copyright Siemens AG 2018 All rights reserved User created F-blocks This chapter shows you the different options for shortening the compilation and program runtime. Depending on the use it will not always be possible to use all suggestions. They nevertheless provide information why certain programming methods cause shorter compilation and program runtimes then a non-optimized program. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 112 5 STEP 7 Safety in the TIA Portal 5.12 Optimizing the compilation and program runtime 5.12.1 Avoiding of time-processing blocks: TP, TON, TOF Every time-processing block (TP, TON, TOF) requires additional blocks and global data corrections in the protection code. Recommendation Use these blocks as little as possible. 5.12.2 Avoiding deep call hierarchies Deep call hierarchies enlarge the code of the system-created F blocks, since a larger scope of protective functions and test is required. When the nesting depth of 8 is exceeded, the TIA Portal will emit a warning during the compilation. Recommendation Copyright Siemens AG 2018 All rights reserved Structure your program in a way as to avoid unnecessary deep call hierarchies. 5.12.3 Avoiding JMP/Label structures If a block call is jumped via JMP/LABEL this leads to an additional protection in the F blocks on the system side. Here, a correction code has to be carried out for the skipped block call. This costs performance and time in the compilation Recommendation Avoid JMP/Label structures as far as possible to reduce F-blocks on the system side. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 113 5 STEP 7 Safety in the TIA Portal 5.13 Data exchange between standard program and F program 5.13 Data exchange between standard program and F program In some cases it is necessary to exchange data between the safety program and the standard user program. The following recommendations should urgently be noted in order to guarantee data consistency between standard and the safety program. Recommendations * No data exchange via bit memory (see chapter 4.2 No bit memory but global data blocks) * Concentrate the access between safety program and the standard user program on two standard DBs. Changes in the standard program will therefore have no influence on the safety program. The controller also does not need to be in STOP mode to load the standard program. Copyright Siemens AG 2018 All rights reserved Figure 5-10: Data exchange between standard and safety program Standard user program Main Safety program FOB1 Data buffer Standard DataToSafety MainSafety InstMainSafety DataFromSafety Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 114 5 STEP 7 Safety in the TIA Portal 5.14 Testing the safety program 5.14 Testing the safety program In addition to the always controllable data of a standard-user program you can change the following data of a safety program in the deactivated safety mode. * Process image of F-I/O * F-DBs (except DB for F-runtime group communication), instance-DBs of F-FBs * F-I/O DBs * Controlling F-I/O is only possible in F-CPU RUN mode. * From a watch table you can control a maximum of 5 inputs/outputs in a safety program. * You can use several watch tables. * As trigger point you need to set "permanent" or "once" for "cycle start" or "cycle end". * Forcing is not possible for the F-I/O. * If you still wish to use stop points for testing, you need to deactivate the safety mode beforehand. This leads to the following errors: Copyright Siemens AG 2018 All rights reserved Properties - Error during communication with the F-I/O - Error at fail-safe CPU-CPU communication Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 115 5 STEP 7 Safety in the TIA Portal 5.15 STOP mode in the event of F errors 5.15 STOP mode in the event of F errors Copyright Siemens AG 2018 All rights reserved In the following cases, the STOP mode is triggered for F-CPUs: 5.16 * In the "System blocks" folder you must not add, change or delete any blocks. * There must not be any access to instance DBs of F-FBs which are not called in the safety program. * The "Maximum cycle time of the F-runtime group" must not be exceeded. Select the maximal permitted time for "Maximum cycle time der F run-time group" which can elapse between two calls of this F runtime group (maximum 20000 ms). * If tags are read from a DB for F runtime group communication whose runtime group is not processed (main safety block of the F runtime group is not called). * Editing the start values in instance DBs of F-FBs is not permitted online and offline and can lead to STOP of the F-CPU. * The main safety block must not contain any parameters since they cannot be supplied. * Outputs of F-FCs must always be initialized. Migration of safety programs Information on migrating safety programs is available at: https://support.industry.siemens.com/cs/ww/en/view/109475826 5.17 General recommendations for safety Generally, the following recommendations apply for handling STEP 7 Safety and F modules. * Whenever possible, always use F controllers. Thus, a later expansion of safety functions can be realized very easily. * Always use one password for the safety program to prevent unauthorized changes. The password is set in the "Safety administration" editor. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 116 6 Automatically generate visualization using the user program 6 Automatically generate visualization using the user program 6.1 Introduction As of TIA Portal V14, you can use the SiVArc (SIMATIC Visualization Architect) option package to automatically generate the visualization of your plant from a visualization library and the user program in the controller. In this chapter you optimize your user program for use with SiVArc. Advantages of generation with SiVArc * Automatic generation of the visualization with process connection * Standardization of user interfaces * Simple and consistent adaptations to operating screens Siemens AG 2018 All rights reserved Requirements The basic requirement for the use of SiVArc is a high degree of standardization of your plant. Modularizing the system into individual function groups has the advantage that SiVArc can use these function groups to generate and interconnect the operating screen from existing library screens. Standardization of the interfaces contributes to efficient work and automatic generation of the visualization. Compliance with the general recommendations of this programming guide will help you. Note SiVArc is an interface topic between HMI and controller. This section looks at SiVArc from the control side. The following links will give you an insight into the functionality of SiVArc: Application example "SiVArc Getting Started" https://support.industry.siemens.com/cs/ww/en/view/109740350 Manual SiVArc https://support.industry.siemens.com/cs/ww/en/view/109755214 SITRAIN course: SIMATIC Visualization Architect, automatic HMI generating https://support.industry.siemens.com/cs/ww/en/view/109758628 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 117 6 Automatically generate visualization using the user program 6.2 How automatic generation works Standardized blocks, e.g. for engine control, are called up in your user program. Using so-called SiVArc rules, you link the called blocks with visualization elements (text fields, IO fields, image blocks, etc.). Figure 6-1: Example call hierarchy in the control system PLC HMI MachineCall Tank 1 Module 1 Module 2 InstConveyor instTank instTank instTank InstConveyor instAxis InstAxis Siemens AG 2018 All rights reserved InstAxis Actors conveyor Tank Axis SiVArc uses the rules to generate the specified visualization element on a copy of an image template for each call of the specified block. Figure 6-2: SiVArc rule Note You also have the option of restricting or blocking the execution of the rule in the controller. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 118 6 Automatically generate visualization using the user program 6.3 Controlling the HMI generator You have the following options for controlling the HMI generator: * Disable SiVArc generation for specific calls * Sort SiVArc generation by function or plant location * Add further properties to SiVArc generation In SiVArc rules, you can use the following information from the controller, among other things: * Network comments * SiVArc variable This gives you the option of providing additional information for SiVArc in the controller, which you can use as a condition in the SiVArc rules. Siemens AG 2018 All rights reserved 6.3.1 Using network comments for control In the network comments, you can add information on controlling the generator that the SiVArc rules search for during generation: Figure 6-3: Network commentary with SiVArc extension In the rule editor, use the "Contains" function in the "Condition" column and search for the information, e.g. "Contains(Block.NetworkComment, "String")". Figure 6-4: Use Network Comment in Rule With this function you have a free design framework to restrict the execution of rules or to execute a rule only for some networks. Recommendation Clearly mark the information for SiVArc generation in the network comments, e.g. "SiVArc: Generate True". Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 119 6 Automatically generate visualization using the user program 6.3.2 Using SiVArc variables for control You can define special SiVArc variables for each network in the device and use these variables in the SiVArc rules. To create SiVArc tags, proceed as follows: 4. Open the block. 5. Switch to the "Plug-Ins" tab in the Inspector window. 6. For each network, enter the name of the variable in the Name column and a value as a string in the "Value" column. Siemens AG 2018 All rights reserved Figure 6-5: Creating SiVArc Variables In the rule editor, you can query the SiVArc variables with the expression "variable name = "value"" and thereby influence the exercise of the rule. In the rule editor, enter the SiVArc variable in the "Condition" column, e.g. "Location = "Bottling West"". In this example, the rule is only executed if the SiVArc variable "Location" has been set to the value "Bottling West" in the network to be generated. Figure 6-6: Use SiVArc variable in rule Recommendation Use common variable names to control the generator to simplify rule creation. The following table shows an example of SiVArc variables: Table 8: Example for SiVArc variables Name Value Meaning Generate true, false SiVArc generates elements for this network. Location Bottling West, Mixing etc. You can automatically assign elements to an HMI image using this function. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 120 6 Automatically generate visualization using the user program Note 6.4 You must define the effects listed in the "Meaning" column yourself using the conditions in the rule editor. The SiVArc variables themselves have no influence on the generator. Additional recommendations Use only characters supported by WinCC Only use characters that are supported by WinCC for the designation of variables. When generating the images, SiVArc accesses the identifiers of data blocks, variables or network comments. SiVArc removes all characters that are not supported by WinCC. This leads to inconsistencies in the project. Characters not supported: * %,@, ?, ", /, \, <, >, ., : Calling the blocks with programming language FBD Siemens AG 2018 All rights reserved So that you can control the generator via network comments or SiVArc variables, call the blocks from which visualization elements are to be generated in the programming language FBD. Note This recommendation applies up to and including TIA Portal V15. As of TIA Portal V15.1, SCL modules can also be used. Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 121 7 The most important recommendations 7 The most important recommendations * Use optimized blocks - * Use data type VARIANT instead of ANY - * Siemens AG 2018 All rights reserved Chapter 3.6.5 Access to I/O areas with PLC data types Using libraries for storing program elements - * Chapter 3.6.2 ARRAY data type and indirect field accesses Creating PLC data types - * Chapter 3.6 Symbolic addressing When handling data, work with ARRAY - * Chapter 3.2.9 Reusability of blocks Symbolic programming - * Chapter 3.2.5 Multi-instances Reusable programming of blocks - * Chapter 3.2 Program blocks Inserting instructions as multi-instance (TON, TOF ..) - * Chapter 2.8.5 Data type VARIANT Structuring the program clearly and well - * Chapter 2.6 Optimized blocks Chapter 3.7 Libraries No bit memory but global data blocks - Chapter 4.2 No bit memory but global data blocks Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 122 8 Appendix 8 Appendix 8.1 Service and support Industry Online Support Do you have any questions or need assistance? Siemens Industry Online Support offers round the clock access to our entire service and support know-how and portfolio. The Industry Online Support is the central address for information about our products, solutions and services. Product information, manuals, downloads, FAQs, application examples and videos - all information is accessible with just a few mouse clicks: https://support.industry.siemens.com Technical Support Siemens AG 2018 All rights reserved The Technical Support of Siemens Industry provides you fast and competent support regarding all technical queries with numerous tailor-made offers - ranging from basic support to individual support contracts. Please send queries to Technical Support via Web form: www.siemens.com/industry/supportrequest SITRAIN - Training for Industry We support you with our globally available training courses for industry with practical experience, innovative learning methods and a concept that's tailored to the customer's specific needs. For more information on our offered trainings and courses, as well as their locations and dates, refer to our web page: www.siemens.com/sitrain Service offer Our range of services includes the following: * Plant data services * Spare parts services * Repair services * On-site and maintenance services * Retrofitting and modernization services * Service programs and contracts You can find detailed information on our range of services in the service catalog web page: https://support.industry.siemens.com/cs/sc Industry Online Support app You will receive optimum support wherever you are with the "Siemens Industry Online Support" app. The app is available for Apple iOS, Android and Windows Phone: https://support.industry.siemens.com/cs/ww/en/sc/2067 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 123 8 Appendix 8.2 Links and literature Table 8-1: Links and literature Siemens AG 2018 All rights reserved Topic \1\ Siemens Industry Online Support https://support.industry.siemens.com \2\ Download page of the entry https://support.industry.siemens.com/cs/ww/en/view/81318674 \3\ Programming Styleguide for S7-1200 and S7-1500 https://support.industry.siemens.com/cs/ww/en/view/81318674 \4\ Library with general functions for (LGF) for STEP 7 (TIA Portal) and S7-1200 / S7-1500 https://support.industry.siemens.com/cs/ww/en/view/109479728 \5\ Libraries with PLC data types (LPD) for STEP 7 (TIA Portal) and S7-1200 / S7-1500 https://support.industry.siemens.com/cs/ww/en/view/109482396 \6\ TIA Portal - An Overview of the Most Important Documents and Links https://support.industry.siemens.com/cs/ww/en/view/65601780 \7\ STEP 7 (TIA Portal) manuals https://support.industry.siemens.com/cs/ww/en/ps/14673/man \8\ S7-1200 (F) Manuals https://support.industry.siemens.com/cs/ww/en/ps/13683/man \9\ S7-1500 (F) Manuals https://support.industry.siemens.com/cs/ww/en/ps/13716/man \10\ ET 200SP CPU manuals https://support.industry.siemens.com/cs/ww/en/ps/13888/man \11\ S7-1200 Getting Started https://support.industry.siemens.com/cs/ww/en/view/39644875 \12\ S7-1500 Getting Started https://support.industry.siemens.com/cs/ww/en/view/78027451 \13\ SIMATIC S7-1200 / S7-1500 Comparison List for Programming Languages Based on the International Mnemonics https://support.industry.siemens.com/cs/ww/en/view/86630375 Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 124 8 Appendix 8.3 Change documentation Table 8-2: Change documentation Version Date Modifications V1.0 09/2013 First version V1.1 10/2013 Corrections in the following chapters: 2.6.3 Processor-optimized data storage for S7-1500 2.12 User constants 3.2.2 Functions (FC) 3.2.3 Function blocks (FB) 3.4.3 Local memory V1.2 03/2014 New chapters: 2.6.4 Conversion between optimized and non-optimized tags 2.6.6 Communication with optimized data 2.9.1 MOVE instructions 2.9.2 VARIANT instructions 3.6.5 Access to I/O areas with PLC data types Siemens AG 2018 All rights reserved Corrections in the following chapters: 2.2 Terms 2.3 Programming languages 2.6 Optimized blocks 2.10 Symbolic and comments 3.2 Program blocks 3.5 Retentivity 4.3 Programming of "Cycle bits" Various corrections in different chapters V1.3 09/2014 New chapters: 2.8.4 Unicode data types 2.10.2 Comment lines in watch tables 2.12 User constants 3.2.10 Auto numbering of blocks 5 STEP 7 Safety in the TIA Portal Corrections in the following chapters: 2.7 Block properties 2.8 New data types for S7-1200/1500 2.9 Instructions 2.10 Symbolic and comments 3.6.4 STRUCT data type and PLC data types 3.7 Libraries Various corrections in different chapters Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 125 8 Appendix Version Date Modifications V1.4 11/2015 New chapters: 2.6.5 Parameter transfer between blocks with optimized and non-optimized access 3.3.3 Overview for transfer of parameters 3.10.5 Correct use of FOR, REPEAT and WHILE loops 5.12 Optimizing the compilation and program runtime V1.5 03/2017 New chapter: 2.7.3 Block interface - hide block parameters (V14 or higher) 2.9.4 Comparison of tags from PLC data types (V14 or higher) 2.9.5 Multiple assignment (V14 or higher) 3.2.6 Transferring instance as parameters (V14) 3.6.3 Formal parameter Array [*] (V14 or higher) 3.6.7 SCL networks in LAD and FBD (V14 and higher) 3.10.4 Structuring with the keyword REGION (V14 or higher) 3.10.11 Unnecessary IF instruction Several corrections in different chapter 12/2018 Siemens AG 2018 All rights reserved V1.6 New chapter: 6 Automatically generate visualization using the user program Update of title page and legal information Programming Guideline for S7-1200/1500 Entry ID: 81318674, V1.6, 12/2018 126