Siemens SIMATIC S7-1500 System Manual page 139

Failure scenario
①
②
③
④
⑤
⑥
Figure 5-43 Failure of both PROFINET cables in the PROFINET ring at the primary CPU
Sequence of events
1. Both PROFINET cables in the PROFINET ring at the primary CPU fail. The redundant system
will not execute a primary-backup switchover. The redundant system will remain in the
RUN-Redundant system state.
2. The primary CPU can no longer access the IO devices in the PROFINET ring. The IO devices
will return to the substitute values.
3. The failure of both PROFINET cables affects the process, since the IO devices in the
PROFINET ring can no longer be reached from the primary CPU.
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Primary CPU
Backup CPU
Two fiber-optic cables (redundancy connections)
IO device ET 200SP
IO device ET 200MP
PROFINET cables (PROFINET ring) → interrupted
Application planning
5.5 Failure scenarios
139