Siemens SIMATIC S7-1500 System Manual page 125

Failure scenario
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②
③
④
⑤
Figure 5-36 Failure of an IO device in the PROFINET ring (using S7-1500R as an example)
Sequence of events
1. An IO device in the PROFINET ring fails.
2. The PROFINET ring is interrupted.
3. The redundant system selects an alternative connection over the backup CPU. This allows
the redundant system to access all remaining IO devices in the PROFINET ring again.
4. The failure of the IO device has an impact on the process. If the failed inputs and outputs
have an important function in the system, their failure can have a critical impact on the
process.
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Primary CPU
Backup CPU
PROFINET cable (redundancy connections, PROFINET ring)
IO device ET 200MP
IO device ET 200SP → failed
Application planning
5.5 Failure scenarios
125