Siemens SIMATIC S7-1500 System Manual page 135

Failure scenario
①
②
③
④
⑤
⑥
Figure 5-41 Failure of both redundancy connections
Sequence of events
1. The two redundancy connections (fiber-optic cables) are interrupted ≤ 55 ms apart.
2. The redundant system switches to an undefined system state: The primary CPU remains in
the RUN operating state. The backup CPU becomes the primary CPU and remains in RUN
operating state.
3. The two primary CPUs continue to exchange process data with the PROFINET devices.
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Primary CPU
Backup CPU
Two fiber-optic cables (redundancy connections) → interrupted
IO device ET 200SP
IO device ET 200MP
PROFINET cable (PROFINET ring)
Application planning
5.5 Failure scenarios
135