Siemens SIMATIC S7-1500 System Manual page 145

Failure scenario
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③
④
⑤
⑥
⑦
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Figure 5-46 Primary CPU failure in PROFINET rings with R1 and S1 devices
Sequence of events
1. The primary CPU of the redundant system fails in RUN-Redundant system state.
2. The redundant system switches to the backup CPU. The backup CPU becomes the new
primary CPU. The redundant system switches to the RUN-Solo system state.
3. The R1 and S1 devices in PROFINET ring 2 can still be accessed via the new primary CPU.
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Primary CPU → failed
Backup CPU → becomes new primary CPU
Two fiber-optic cables (redundancy connections)
PROFINET cable (PROFINET ring 1)
PROFINET cable (PROFINET ring 2)
IO device ET 200SP HA (R1 device)
IO device ET 200SP (R1 device)
IO device ET 200pro (S1 device) → no longer accessible, because PROFINET ring 1 assigned
IO device ET 200SP (S2 device, reparameterized to an S1 device) → no longer accessible,
because PROFINET-Ring 1 assigned
IO device ET 200SP (S2 device, reparameterized to an S1 device)
IO device ET 200pro (S1 device)
Application planning
5.5 Failure scenarios
145