Siemens Simatic S7-1500R System Manual page 68

Sequence of events
1. One of the two redundancy connections (fiber-optic cables) is interrupted.
2. The primary CPU continues to exchange process data with the IO devices.
3. The redundancy of the system is restricted. The redundant system will remain in the
RUN-Redundant system state. The restriction has no effect on the process.
If the primary CPU fails as well as the redundancy connection, the backup CPU switches
to the STOP operating state. You can find additional information in the section Failure
scenarios (Page 72).
Diagnostics
System state, operating states and error displays after the failure of a redundancy
connection:
● Redundant system → RUN-Redundant system state
● Primary CPU → RUN-Redundant operating state
– MAINT LED → yellow light: There is only one redundancy connection remaining in the
● Backup CPU → RUN-Redundant operating state
– MAINT LED → yellow light: There is only one redundancy connection remaining in the
Note
To get detailed diagnostics information, evaluate the diagnostics buffer.
Solution
Replace the defective redundancy connection. 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
H system.
H system.
Application planning
3.4 Redundancy scenarios
67