Transmitting IPC flags in
multiprocessor operation
At the end of each program cycle, along with the updating of the
process image, the CPU transmits the IPC flags specified in DB 1
when the coordinator signals the CPU that it can access the S5 bus.
The coordinator allocates the bus enable signal to each CPU in
sequence. When a CPU has access to the S5 bus, it can transmit only
one byte. Because of this interleaved transmission, related (byte
groups) IPC flag information can be separated and subsequently
processed with old or incorrect values.
If you want to transfer information that takes up more than one byte,
you can prevent corruption of data by setting a parameter in extended
data block DX 0. This parameter uses semaphores to ensure that all
IPC flags specified in DB 1 are transferred in groups (see Chapter 7).
While one CPU is transmitting IPC flags, another CPU cannot
interrupt it. Because the next CPU has to wait to transmit its data,
cyclic program processing of this CPU is delayed accordingly.
Under certain circumstances, the setting you make in DX 0 can
increase the cycle time considerably.
Multiprocessor
communication
For transferring data blocks or more exactly fields of data with a size
of max. 64 byte (= 32 data words), the following special functions are
integrated in the CPU:
••
OB 200: INITIALIZE:
preassign
••
OB 202: SEND:
send a data field
••
OB 203: SEND TEST:
test sending capacity
••
OB 204: RECEIVE:
receive a data field
••
OB 205: RECEIVE TEST:
test receiving capacity
10.1.4
Exchanging Data via
Handling Blocks
Handling blocks are capable of multiprocessing. A special parameter
assignment for the multiprocessor mode is not necessary. For more
information on handling blocks refer to the appropriate manual.
Multiprocessor Mode
CPU 948 Programming Guide
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C79000-G8576-C848-04
Summary of Contents for CPU 948
Page 10: ...Contents CPU 948 Programming Guide 1 2 C79000 G8576 C848 04 ...
Page 32: ...Contents CPU 948 Programming Guide 2 2 C79000 G8576 C848 04 ...
Page 72: ...Data Blocks CPU 948 Programming Guide 2 42 C79000 G8576 C848 04 ...
Page 74: ...Contents CPU 948 Programming Guide 3 2 C79000 G8576 C848 04 ...
Page 154: ...Contents CPU 948 Programming Guide 4 2 C79000 G8576 C848 04 ...
Page 200: ...Contents CPU 948 Programming Guide 5 2 C79000 G8576 C848 04 ...
Page 308: ...Contents CPU 948 Programming Guide 7 2 C79000 G8576 C848 04 ...
Page 324: ...Examples of Parameter Assignment CPU 948 Programming Guide 7 18 C79000 G8576 C848 04 ...
Page 326: ...Contents CPU 948 Programming Guide 8 2 C79000 G8576 C848 04 ...
Page 370: ...Addressable System Data Area CPU 948 Programming Guide 8 46 C79000 G8576 C848 04 ...
Page 372: ...Contents CPU 948 Programming Guide 9 2 C79000 G8576 C848 04 ...
Page 486: ...Contents CPU 948 Programming Guide 11 2 C79000 G8576 C848 04 ...
Page 522: ...PG Functions via the S5 Bus CPU 948 Programming Guide 11 38 C79000 G8576 C848 04 ...
Page 524: ...Contents CPU 948 Programming Guide 12 2 C79000 G8576 C848 04 ...
Page 538: ...Contents CPU 948 Programming Guide 13 2 C79000 G8576 C848 04 ...
Page 546: ...List of Key Words CPU 948 Programming Guide Index 6 C79000 G8576 C848 04 ...