Siemens Simatic S7-1500 Function Manual page 66

Failure of the backup CPU
The figure below shows the impact of the failure of the backup CPU on the cycle time.
①
②
③
④
⑤
Figure 5-5
The backup CPU fails before processing of the cyclic program has ended
CPU detects the failure of the backup CPU because no synchronization data has been
received until the monitoring time
synchronization with the backup CPU. The redundant system switches from RUN-
Redundant system state to RUN-Solo system state
Because no more data can be synchronized in RUN operating state, the cycle time
shorter than the cycle time
Cycle and response times
Function Manual, 10/2018, A5E03461504-AD
Cycle and response times of the S7-1500R/H redundant system
5.3 Influences on the cycle time of the S7-1500R/H redundant system
Cycle time
Failure of the backup CPU
Expiration of the monitoring time
System status transition
Cycle time of the primary CPU in RUN-Solo operating state
Impact of the failure of the backup CPU on the cycle time
①
③
has expired. The primary CPU terminates the
④
.
②
. The primary
.
⑤
is
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