Communication blocks
1-6 Function Blocks - SIMATIC TDC
Edition 12.2004
1.2 Central coupling blocks
1.2.1 @GLOB Communications buffer coupling central block
@GLOB
communications buffer module name
GV CTS CDM BO
coupling status
reorganization
BO CDV QTS BO
block status
• the central block @GLOB initializes and monitors the communications
buffer coupling. The communications buffer coupling can be set-up on
all communications buffer modules.
• the function block may only be configured once for each subrack, as
there is only one communications buffer module for each subrack.
Multiple configuring is identified during initialization and results in an
entry in the communications error field.
• the function block may only be configured in the sampling interval
32 ms <= TA <= 256 ms. Otherwise, an entry is made in the
communications error field.
While the function block is being initialized, general preparations are
made to enable the coupling. The coupling is only enabled after the
normal mode has been executed several times.
After the coupling has been enabled, the central block monitors that
transmitters and receivers are correctly logged-on. Further, if required, it
re-organizes and updates the block output CDM at each processing
cycle.
The complete data interface is re-formatted by setting the CDV input.
This option should be used, if
• an application (e.g. the message evaluation function block MSI)
flags that it cannot log-on any additional channel at the data interface, as
there is no sufficient memory space available.
If the CDV block input is set again, this is only taken into account if the
CDV input was reset (i.e. was at 0) for at least 2 sampling times after re-
organization was completed. Otherwise the data at the input is ignored.
The CDM block output provides information about the coupling status.
The output is 1, if the coupling is enabled for general transmit/receive
operation. The CDM block output is 0, as long as the coupling is being
initialized or is being re-initialized (after a temporary fault), or the memory
is being re-formatted (refer to CDV connection).
The computation time information in the technical data refers to a typical
task processing. During re-organization, the computation time is
extended over several processing cycles up to 370 µs.
Symbol
Brief description
Mode of operation