Siemens SIMATIC S7-400H Manual page 214

Failure and Replacement of Components During Operation
Initial situation
Simultaneous Failure of a Fiber–Optic or
Synchronization Module:
The S7-400H is in redundant system mode
and both fiber-optic cables or
synchronization submodules fail.
Procedure
The double error described results in loss of redundancy. In this event proceed as
follows:
Step
1
2
3
4
10-10
Failure
What Has To Be Done?
Switch off a subsystem.
Replace the faulty components.
Turn the subsystem back on.
Start the CPU (e.g. STOP³RUN or
Start via programming device).
How Does the System React?
•
Both CPUs report the event in the
diagnostics buffer and via OB 72.
•
Both CPUs become the master CPU and
remain in RUN mode.
How Does the System React?
LEDs IFM1F and IFMF2F go out. The
standby LED lights.
•
CPU performs automatic LINK-UP
and UPDATE.
•
CPU changes to RUN (Redundant
system mode) and now operates
as the standby CPU.
Automation System S7-400H Fault-tolerant Systems
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A5E00068197-07