Siemens Simatic S7-1500R System Manual page 77

Application planning
3.5 Failure scenarios
Sequence of events
1. A switch (with connected line topology) in the PROFINET ring fails.
2. The PROFINET ring is interrupted.
3. If applicable, the redundant system selects an alternative connection to the IO devices
and
in the PROFINET ring again.
4. The failure of the switch has an impact on the process as the IO devices in the 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.
Diagnostics
System state, operating states and error displays after the failure of a switch:
● Redundant system → RUN-Redundant system state
● Primary CPU → RUN-Redundant operating state
– MAINT LED → yellow light: The PROFINET ring is open.
– ERROR LED → flashes red: One or more IO devices have failed.
● Backup CPU → RUN-Redundant operating state
– MAINT LED → yellow light: The PROFINET ring is open.
– ERROR LED → flashes red: One or more IO devices have failed.
Note
To get detailed diagnostics information, evaluate the diagnostics buffer.
Solution
Replace the defective switch. You can find additional information on the procedure in the
section Replacing defective I/O devices/switches (Page 268).
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over the backup CPU. This allows the redundant system to access all IO devices
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
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