Siemens SIMATIC S7-1500 System Manual page 399

Commissioning
12.4 Operating and system states
You can find a detailed list of causes of errors and solutions in the SYNCUP abort table:
Causes and solutions.
Figure 12-8 SYNCUP system state aborts
Table 12- 12 Sequence of events: SYNCUP aborts
No. in Primary CPU
dia-
gram
Initial situation: The S7-1500R/H redundant system is in the SYNCUP system state. An error occurs in the backup CPU.
① The CPU does not switch from the RUN-Syncup
operating state to RUN-Redundant, but instead
returns to RUN and continues to execute the
user program.
Procedure for error correction
1. Eliminate the error.
2. Switch the backup CPU from STOP to RUN.
The backup CPU switches from STOP to the SYNCUP operating state. Synchronization restarts.
398
System state
SYNCUP → RUN-Solo
Backup CPU
If SYNCUP aborts, the backup
CPU may restart and then
switch to the STOP operating
state. The backup CPU is ready
for a new SYNCUP.
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF