Siemens SIMATIC S7-1500 System Manual page 224

Failure scenario
①
②
③
④
⑤
⑥
⑦
⑧
Figure 6-59
Sequence of events
1. The PROFINET line between two IO devices fails.
2. The redundant system continues to reach all IO devices in the line topology.
3. In addition, the PROFINET line to the backup CPU fails.
4. The redundant system no longer reaches all IO devices in the line topology. These IO devices
fall back to the substitute values.
5. The redundant system will remain in the RUN-Redundant system state: The primary and
backup CPUs remain in the RUN-Redundant operating state.
6. The failure of both PROFINET lines affects the process, as IO devices in the line topology are
no longer accessible.
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
Primary CPU
Backup CPU
Two fiber-optic cables (redundancy connections)
PROFINET lines (line topology)
IO device ET 200MP
IO device ET 200SP
PROFINET line→ interrupted (1st defect)
PROFINET line→ interrupted (2nd defect)
Failure of PROFINET lines in two places in a line topology with S2 devices
Application planning
6.5 Failure scenarios
223