Siemens Simatic S7-1500H - Page 66

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