Testing functions, Diagnostics and Fault Elimination
S7-300 Programmable Controller Hardware and Installation
10-20 A5E00105492-01
Event recognition
The table below shows how CPU 31x-2 operating as DP slave recognized
operating state transitions or data exchange interruptions.
Table 10-11 Event recognition of CPUs 31x-2 operating as DP slave
Event What happens in the DP Slave?
Bus failure interrupt (short-
circuit, connector unplugged)
• Call of OB 86 with the message Station failure
(incoming event; diagnostic address of the DP slave,
assigned to the DP slave)
• with I/O access: Call of OB122 (I/O access error)
DP master: RUN → STOP • Call of OB 82 with the message Module error
(incoming event; diagnostic address of the DP slave
assigned to the DP slave; Variable
OB82_MDL_STOP=1)
DP master: STOP → RUN • Call of OB82 with the message Module OK(outgoing
event; diagnostic address of the DP slave, assigned to
the DP slave; Variable OB82_MDL_STOP=0)
Evaluation in the user program
The table below shows you how you can, for example, evaluate RUN-STOP
transitions of the DP master in the DP slave (see also the previous table).
Table 10-12 Evaluating RUN-STOP transitions in the DP Master/DP Slave
In the DP Master In the DP Slave
Diagnostic addresses: (Example)
Master diagnostic address =1023
Slave diagnostic address in the master
system=1022
Diagnostic addresses: (Example)
Slave diagnostic address =422
Master diagnostic address = irrelevant
CPU: RUN " STOP → The CPU calls OB 82 with the following
information:
• OB 82_MDL_ADDR:=422
• OB82_EV_CLASS:=B#16#39 (incoming
event)
• OB82_MDL_DEFECT: = Module error
Tip: The CPU diagnostic buffer also
contains this information
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