Siemens S5-135U/155U - Manual (Page 277)

6-15
System Manual
C79000-G8576-C199-06
6.4 923A Coordinator Module
6.4.1 Technical Description
This section contains information on the application, design and principle of
operation of the 923A coordinator.
The 923A coordinator module is intended for operation in the S5-135U/155U
PLC. It is required in multiprocessor operation and has the following
functions:
S
Bus arbitration
To coordinate multiprocessor operation, i.e. the simultaneous use of two
to four CPUs (CPU 928B, CPU 928 or CPU 922).
S
Communication memory
for the interchange of data between CPUs via communication flags.
Note
The 923A coordinator module cannot be used in multiprocessor operation if
a CPU 948 is fitted in the 135U/155U PLC. If you execute global memory
access in multiprocessor operation (I/O area with addresses 0000H-EFFFH)
with the CPU 928B and/or the CPU 928, you must use the COR 923C as the
coordinator.
The COR 923A is designed as a plug-in PCB of double Eurocard format.
Two 48-way Series 2 blade connectors serve to connect the PCB to the S5
bus in the subrack.
The front plate width is 1 1/3 standard plug-in stations.
A three-position mode switch is fitted in the front plate for operator
functions.
Application
Design
Multiprocessor Operation/Coordinators