System modifications during operation
17.7 Editing CPU parameters
S7-400H
System Manual, 03/2012, A5E00267695-11
327
Reaction of the I/O
Type of I/O One-sided I/O of previous
master CPU
One-sided I/O of new master
CPU
Switched I/O
I/O modules are no longer addressed by the
CPU.
Output modules output the
configured substitute or holding
values.
are given new parameter
settings
1)
and updated by the
CPU.
continue operation without
interruption.
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
The update is canceled and no change of master takes place if one of the monitored times
exceeds the configured maximum. The fault-tolerant system remains in single mode with the
previous master CPU and, assuming certain conditions are met, attempts the master
changeover later. For additional information, refer to section Time monitoring (Page 155).
Whe
re the va
lues for the monitoring times in the CPUs differ, the higher values always apply.
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