Siemens SIMATIC ET 200AL, System Manual

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Functions
5.5 Intelligent DP slaves (I-slaves)
PROFIBUS with STEP 7 V13
Function Manual, 12/2014, A5E03775446-AC
89
5.5.6 Diagnostics and interrupt behavior
Diagnostics and interrupt behavior
S7 CPUs have numerous diagnostics and interrupt functions that can, for example, report
errors/faults or failures of underlying DP systems. These diagnostics alarms reduce
downtimes and simplify localization and elimination of problems.
Diagnostics options in the higher-level DP master and in the I-slave
The following diagnostics mechanisms are available to the higher-level DP master and the
I-slave:
●
OB 82 (diagnostic interrupt)
When the I-slave changes mode, the DP master calls OB 82 (diagnostic interrupt).
When the DP master changes mode, the I-slave calls OB 82 (diagnostic interrupt).
● OB 86 (rack failure)
If the bus connection to the I-slave is interrupted, the DP master calls OB 86
(rack failure).
If the bus connection to the DP master is interrupted, the I-slave calls OB 86
(rack failure).
● OB 122 (I/O access error)
If you have not set the attribute "Handle errors within block" for OB 122, the following
applies:
–
If the bus connection to the I-slave is interrupted, the DP master calls OB 122
(I/O access error) if there is direct access to the relevant transfer areas.
– If the bus connection to the DP master is interrupted, the I-slave calls OB 122
(I/O access error) if there is direct access to the relevant transfer areas.