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Introduction
Error handling
ACCU condition code bits
RLO ,
CC0/CC1
6 - 6
An error occurring in the execution of the active special function triggers
a special error reaction in the system program.
In terms of this error reaction by the system program, two groups of
special functions can be distinguished.
• • Group 1:
Group 1 includes all the special functions with which IDs are
transferred to ACCU 1 if an error occurs to further explain the
error.
• • Group 2:
With some of the special functions, the RLO or the status bits
CC0/CC1 are written to indicate errors for specific special
functions.
If an error occurs when using one of these special functions, the
RLO is set to "1" in most cases. In your STEP 5 program, you can
use a JC operation (conditional jump) to evaluate the RLO for
these special functions and then react to an error.
In some special functions, the results bits CC0 and CC1 are
affected by the processing of a special function. You can scan
these bits in your STEP 5 program using a compare operation and
once again program a reaction to an error.
Which of the error reactions occurs for the individual special function
OBs is explained in the following sections.
CPU 948 Programming Guide
C79000-G8576-C848-04
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