Siemens SIMATIC S7-1500 System Manual page 210

Failure scenario
①
②
③
④
⑤
Figure 6-52
Sequence
1. The backup CPU fails.
2. The redundant system switches to the RUN-Solo system state.
3. In addition, the CP 1543-1 at the primary CPU fails.
4. The primary CPU switches to the STOP operating state.
5. The redundant system has failed. The process is no longer controlled by the redundant
system.
Diagnostics
System state, operating states, and error displays after the failure of the backup CPU and
failure of the CP at the primary CPU:
• Redundant system → STOP system state
• Primary CPU → STOP operating state
– MAINT LED → lights up yellow: The R/H system is not in the RUN-Redundant system
– ERROR-LED → lights up red: Module failed
• Backup CPU → failed
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
Primary CPU
Backup CPU → failed
CP 1543-1 (at primary CPU) → failed
CP 1543-1 (at backup CPU)
PROFINET cable (redundancy connections, PROFINET ring)
S7-1500R failure of the backup CPU and failure of the CP 1543-1 at the primary CPU
state; no partner CPU was found.
Application planning
6.5 Failure scenarios
209