Technical data

6.26 OB 224: Transferring Blocks of Interprocessor
Communication Flags
Function The interprocessor communication (IPC) flags are transferred at the
end of the program cycle. In the single processor mode, the IPC flags
are transferred completely as a block of data to the memory on the
coordinator or the CP and/or from this memory to the flags of the
CPU. The S5 bus is always available.
In multiprocessor operation, on the other hand, each CPU can only
use the bus when it is allocated by the coordinator. Each time the CPU
has access to the bus, only
one byte is transferred. Following this, it is
once again the turn of the other CPUs. Sets of data that belong
together but that are distributed over several flag bytes are therefore
separated.
If you call organization block OB 224, you can transfer all the IPC
flags specified in DB 1 of the CPU as a block of data. As long as a
CPU is transferring IPC flags, it cannot be interrupted by another
CPU. Since the next CPU has to wait before it can transfer its data, the
cyclic program execution is delayed (cycle time!).
OB 224 ensures the consistency of the IPC flag information. It must
be called in the start-up program as follows:
•• in all the CPUs involved in IPC flag transfer
and
•• in each restart type being used.
Parameters none
Possible errors none
OB 224: Transferring Blocks of Interprocessor
Communication Flags
CPU 928B Programming Guide
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