Pcs 7, Step 3: Stopping The Standby Cpu - Siemens SIMATIC S7-400H Manual

11.2.3

PCS 7, Step 3: Stopping the Standby CPU

Initial situation
The fault-tolerant system is working in redundant system mode.
Procedure
1. In SIMATIC Manager, select a CPU of the fault-tolerant system, and choose the
PLC > Operating Mode menu command.
2. In the Operating Mode dialog box, select the standby CPU and click the Stop
button.
Result
The standby CPU switches to STOP mode, the master CPU remains in RUN
mode, the fault-tolerant system works in single mode. One-way I/O of the standby
CPU are no longer addressed.
Whilst I/O access errors of the one-way I/O will result in OB 85 being called, due to
the superior CPU redundancy loss (OB 72) these will not be reported. OB 70 (I/O
redundancy loss) will not be called.
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
Modifying the System During Operation
11-9