Failure scenario
① Primary CPU
② Backup CPU
③ PROFINET ring → interrupted at two points
④ IO device ET 200MP
⑤ IO device ET 200SP
Figure 5-38Two cable interruptions in the PROFINET ring (>1500ms apart)
Sequence of events
1.
The PROFINET ring is interrupted at one point.
2.
The redundant system remains in the RUN-Redundant system state: The primary and
backup CPUs remain in the RUN-Redundant operating state.
3.
The PROFINET ring is interrupted at a second point >1500ms later.
4.
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.
5.
CPU redundancy has failed. The failure has an impact on the process. The RUN-Solo
system state and the cable interruptions mean that not all IO devices in the PROFINET ring
can be accessed.
If the failed inputs and outputs have an important function in the system, their failure can
have a critical impact on the process.
129
Application planning
5.5 Failure scenarios
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
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