Siemens SIMATIC S7-1500 System Manual page 183

Application planning
6.4 Redundancy scenarios
Redundancy scenario
①
②
③
④
⑤
⑥
Figure 6-37
Sequence of events
1. One of the two redundancy connections (fiber-optic cables) is interrupted.
2. The system continues to exchange process data with the IO devices.
3. The redundancy of the system is restricted. The redundant system will remain in the RUN-
Redundant system state. The restriction has no effect on the process.
182
Primary CPU
Backup CPU
One fiber-optic cable (redundancy connection) → interrupted
IO device ET 200SP
IO device ET 200MP
PROFINET cable (PROFINET ring)
Failure of a redundancy connection
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF