Siemens Simatic S7-300, Hardware And Installation Manual, Page: 180 / 242

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