Siemens CPU 948, Programming Manual

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Program structure During restart, one of the CPUs calls the INITIALIZE function (OB
200) to reserve exactly the same number of coordinator memory fields
per link as data fields to be transmitted on this link.
To send and receive data word areas, each CPU uses two function
blocks:
FB no. Name Function
FB 100
FB 101
SEND-DAT
RECV-DAT
Send data word areas
to the other CPUs
Receive data word areas
from the other CPUs
These FB numbers have been selected at random and you can use
others.
The function blocks SEND-DAT and RECV-DAT read the link list to
determine which data word areas are to be sent from or received by which
data blocks. The whole data word area is always sent or received. If this
is not possible owing to insufficient transmitting or receiving capacity, the
send or receive function is not executed.
Note
This example (IPC flag extension using function blocks
SEND-DAT and RECV-DAT) can only run correctly when the
special function organization blocks for multiprocessor
communication OB 202 to OB 205 are not called in any of the
CPUs.
The function blocks SEND-DAT and RECV-DAT contain the
special function organization blocks for multiprocessor
communication OB 202 to OB 205. You cannot call these
organization blocks outside SEND-DAT/RECV-DAT.
Applications
CPU 948 Programming Guide
10 - 70
C79000-G8576-C848-04