Step 5: Transition To Redundant System Mode - Siemens SIMATIC S7-400H System Manual

17.9.6

Step 5: Transition to redundant system mode

Starting situation
The fault-tolerant system operates with the modified parameters in single mode.
Procedure
1. In SIMATIC Manager, select a CPU of the fault-tolerant system, then choose "PLC >
2. From the "Operating Mode" dialog box, select the reserve CPU, then click "Warm
Result
The reserve CPU links up and is updated. The fault-tolerant system is operating in redundant
system mode.
Reaction of the I/O
Type of I/O
I/O modules
1) Central modules are first reset. Output modules briefly output 0 during this time (instead of the configured substitute or
hold values).
Reaction to monitoring timeout
If one of the monitored times exceeds the configured maximum the update is canceled. The
fault-tolerant system remains in single mode with the previous master CPU and, assuming
certain conditions are met, attempts the link-up and update later. For additional information,
refer to section Time monitoring (Page 155).
If the values for the monitoring times in the CPUs differ, the higher values apply.
S7-400H
System Manual, 03/2012, A5E00267695-11
Operating Mode" from the menu.
Restart".
One-sided I/O of reserve CPU
are given new parameter
settings and updated by the
1)
CPU.
System modifications during operation
17.9 Re-parameterization of a module
One-sided I/O of master CPU
continue operation without interruption.
Switched I/O
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