Siemens SIMATIC S7-1500 System Manual page 202

Failure scenario
①
②
③
④
⑤
⑥
⑦
⑧
Figure 6-48
Sequence of events
1. A switch (with additional line topology) fails in the PROFINET ring.
2. The PROFINET ring is interrupted.
3. If applicable, the redundant system selects an alternative connection to the IO devices ④
and ⑤ over the backup CPU. This allows the redundant system to access all IO devices in the
PROFINET ring again.
4. The failure of the switch has an impact on the process as the IO devices in the additional line
topology can no longer 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.
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
Primary CPU
Backup CPU
PROFINET cable (redundancy connections, PROFINET ring)
IO device ET 200MP
IO device ET 200SP
Switch → failed
IO device ET 200SP
HMI device
Failure of a switch in the PROFINET ring (using S7-1500R as an example)
Application planning
6.5 Failure scenarios
201