Siemens SIMATIC S7-1500 System Manual page 185

Application planning
6.4 Redundancy scenarios
Redundancy scenario
①
②
③
④
⑤
⑥
Figure 6-38
Sequence of events
1. The two redundancy connections (fiber-optic cables) are interrupted > 55 ms apart.
2. The redundant system switches to the RUN-Solo system state. The primary CPU remains in
the RUN operating state. The backup CPU switches to the STOP operating state.
3. The primary CPU continues to exchange process data with the IO devices.
4. The redundancy of the system is restricted. The restriction has no impact on the process.
If another system component or another network segment fails, this can result in the failure
of the S7-1500R/H redundant system. You can find additional information in the section
Failure scenarios (Page 198).
184
Primary CPU (S7-1500H)
Backup CPU (S7-1500H)
Two fiber-optic cables (redundancy connections) → interrupted
IO device ET 200MP
IO device ET 200SP
PROFINET cable (PROFINET ring)
Failure of both redundancy connections (> 55 ms apart)
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF