Siemens S5-135U/155U User Manual

Page 273

6-11

System Manual
C79000-G8576-C199-06

Executing a RESET at all CPUs:

Action

Reaction

Execute a RESET at each individual
CPU:
Hold the MC

mode switch at the

RESET setting; simultaneously set the
mode switch from STOP to RUN.

The red STOP LED on each CPU
is continuously lit; each CPU
emits the output inhibit signal.
The CPUs are in the wait state.

MC: Momentary-contact

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:

Is the coordinator inserted?

Are all modules correctly inserted (engaged)?

Are all modules at the correct slots?

Step 7

Possible Faults

Multiprocessor Operation/Coordinators