Communication blocks
Function Blocks - FM 458-1 DP
2-15
Edition 12.2004
2.3 FM 458-specific coupling
2.3.1 @CPB P-bus, central coupling block
@CPB
CPU-module-name.PBUS
―
GV CTS CDM
BO
―
coupling status
QTS
BO
―
block status
The central block for the P-bus coupling can only run with an FM 458
application module.
•
This function block is responsible for initializing and monitoring the P
bus coupling.
•
The function block can only be configured once for each application
module FM 458, as there is only one P-bus coupling for each FM 458.
If a function block is configured a multiple number of times, this is
detected when initializing, and results in an entry in the
communications error field.
•
The block may only be configured in the sampling interval
32 ms <= TA <= 256 ms. Otherwise, an entry is made in the
communications error field.
When initializing the function block, general preparations are made to
enable the coupling. The coupling is only enabled after the standard
mode has been run-through (executed) several times.
After the coupling has been enabled, the central block monitors that
senders and receivers are correctly registered. Further, if required, it re-
organizes and updates the block output CDM at each processing cycle.
The function block cannot be used to initialize another P-bus coupling or
monitor this. It can only initialize its own P-bus coupling on which CPU is
configured. An entry is made in the communications error field if another
module name is specified at the CTS input (other than its own).
The CDM block output provides information about the coupling status.
The connection is a 1, if the coupling is enabled for general send/receive
operation. The CDM block output is 0, as long as the coupling is still
being initialized, or is being re-initialized (after a temporary fault).
Symbol
Brief description
Mode of operation
