Siemens CPU 948, Programming Manual

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Results bits The results bits (CC 1/CC 0, RLO etc.) are influenced by the
communication OBs. For more detailed information refer to Section
10.2.8.
Changes in the ACCUs
••
CPU 922, CPU 928,
CPU 928B: The contents of ACCU 1 to ACCU 4 and the
contents of the registers are not affected by
the communication OBs.
••
CPU 946/947,
CPU 948:
The contents of all registers and ACCU 1, 2
and 3 remain the same, only the contents of
ACCU 4 are affected.
10.2.7
How to Assign Parameters
to Communication OBs
The communication OBs have the following types of parameter:
••
input parameters,
••
output parameters
and
••
call parameters.
Input and output parameters are located in a maximum 10 byte long
data field in the F flag area. The data field is divided into an area for
input parameters and an area for output parameters.
Input parameters
The input parameters specify how a function is handled. All or part of
the parameters are read out by communication OBs and evaluated, no
write access takes place.
Output parameters
The output parameters contain all the information that the calling
program needs about the result of a job, e.g. error bits.
Some or all of the output parameters are written to by the
communication OBs, this area is not read.
Note
You can assign a flag area with 10 flag bytes for all
communications functions. The functions themselves require
different numbers of bytes. Refer to the description of the single
functions (Section 10.4ff).
Multiprocessor Communication
CPU 948 Programming Guide
C79000-G8576-C848-04
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