Siemens SIMATIC S7-1500 System Manual page 107

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Figure 5-26 Failure of a PROFINET cable in the PROFINET ring (using S7-1500R as an example)
Sequence of events
1. A defective or disconnected PROFINET cable interrupts the PROFINET ring of the redundant
system.
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 redundant system selects an alternative connection over the backup CPU. This allows
the redundant system to access all IO devices in the PROFINET ring again.
4. The redundancy of the system is restricted. The restriction has no effect on the process.
If another system component or another network segment fails, this can result in the
failure of the S7-1500R/H redundant system.
– If the PROFINET cable is also interrupted at another point, IO devices in the PROFINET
– You can find additional information in the section Failure scenarios (Page 124).
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Primary CPU
Backup CPU
PROFINET cable (redundancy connections, PROFINET ring) → interrupted
IO device ET 200MP
IO device ET 200SP
ring may fail depending on the location of the interruption.
Application planning
5.4 Redundancy scenarios
107