Siemens Simatic S7-1500R System Manual page 70

Sequence of events
1. The two redundancy connections (fiber-optic cables) are interrupted, one > 1500 ms after
the other.
2. 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.
3. The primary CPU continues to exchange process data with the IO devices.
4. The redundancy of the system is restricted. The restriction has no impact 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. You can find additional information in the
section Failure scenarios (Page 72).
Diagnostics
System state, operating states and error displays after the failure of both redundancy
connections:
● Redundant system → RUN-Solo system state
● Primary CPU → RUN operating state
– MAINT LED → yellow light: The H-system is not in the RUN-Redundant system state.
● Backup CPU → STOP operating state
– MAINT LED → yellow light: The H-system is not in the RUN-Redundant system state.
Note
To get detailed diagnostics information, evaluate the diagnostics buffer.
Solution
Replace the defective redundancy connections. You can find additional information on the
procedure in the section Replacing defective redundancy connections (Page 261).
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
No partner CPU has been found in the H-system.
No partner CPU has been found in the H-system.
Application planning
3.4 Redundancy scenarios
69