Siemens S5-135U/155U System Manual page 273

Step 7
Executing a RESET at all CPUs:
Execute a RESET at each individual
CPU:
Hold the MC
RESET setting; simultaneously set the
mode switch from STOP to RUN.
1)
Possible Faults Symptom 1:
The STOP LED of one CPU flashes slowly. When the control bits of this
CPU are read out with the programmer, "DB 1 error" is marked in addition to
the usual information. There is no output of an ISTACK.
Remedy:
Check whether data block DB1 in the CPU was correctly loaded and
programmed.
Symptom 2:
After execution of a RESET:
Undefined states or faults occur at the CPUs (e.g. after a RESTART at
CPU 922, it goes to the RUN state although the other CPUs are still at
STOP).
Remedy:
Verify the following points:
System Manual
C79000-G8576-C199-06
Action
1)
mode switch at the
MC: Momentary-contact
Is the coordinator inserted?
Are all modules correctly inserted (engaged)?
Are all modules at the correct slots?
Multiprocessor Operation/Coordinators
Reaction
The red STOP LED on each CPU
is continuously lit; each CPU
emits the output inhibit signal.
The CPUs are in the wait state.
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