Siemens Simatic S7-1500R System Manual page 79

Application planning
3.5 Failure scenarios
Sequence of events
1. The PROFINET ring is interrupted at one point.
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 PROFINET ring is interrupted at a second point > 1500 ms later.
4. The redundant system switches to the RUN-Solo system state. The primary CPU remains
in the RUN operating state. The backup CPU switches to the STOP operating state.
5. CPU redundancy has failed. The failure has an impact on the process. The RUN-Solo
system state and the cable interruptions mean that not all IO devices in the PROFINET
ring can 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 cable interruptions:
● Redundant system → RUN-Solo system state
● Primary CPU → RUN operating state
– MAINT LED → yellow light: The R system is not in the RUN-Redundant system state.
– ERROR LED → flashes red: One or more IO devices cannot be accessed.
● Backup CPU → STOP operating state
– MAINT LED → yellow light: The R system is not in the RUN-Redundant system state.
– ERROR LED → flashes red: One or more IO devices cannot be accessed.
Note
To get detailed diagnostics information, evaluate the diagnostics buffer.
Solution
Replace the defective PROFINET cables. You can find additional information on the
procedure in the section Replacing defective redundancy connections (Page 261).
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No partner CPU has been found in the R system. The PROFINET ring is open.
No partner CPU has been found in the R system. The PROFINET ring is open.
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA