Siemens Simatic S7-1500R System Manual page 72

Sequence of events
1. Both redundancy connections (fiber-optic cables) fail in the redundant system. The time
between the failures is > 1500 ms.
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. A defective PROFINET cable also interrupts the PROFINET ring.
4. The redundant system accesses all IO devices in the PROFINET ring again over the
remaining PROFINET cables.
5. The redundancy of the system is restricted. The restrictions have no effect on the
process.
Diagnostics
System state, operating states and error displays after the failure of the redundancy
connections and PROFINET cable:
● 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 and the defective PROFINET cable. You can
find more information on the procedure in the following sections:
● Replacing defective redundancy connections (Page 261)
● Replacing defective PROFINET cables
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
No partner CPU has been found in the H-system. The PROFINET ring is open.
No partner CPU has been found in the H-system. The PROFINET ring is open.
Application planning
3.4 Redundancy scenarios
71