Siemens SIMATIC S7-1500 System Manual page 390

SYNCUP system state
Synchronization in the SYNCUP system state ensures that the two CPUs can operate
redundantly. With the SYNCUP system state, the redundant system switches from RUN-Solo
to the RUN-Redundant system state. Afterwards, both CPUs synchronously process the same
user program.
Starting SYNCUP
The initial situation is the RUN-Solo system state. The primary CPU of a redundant system is in
the RUN operating state and the backup CPU is in the STOP operating state.
The operating states are shown on the displays:
Table 12- 4
Start SYNCUP by:
• Starting the backup CPU via the PG/PC/HMI device or the display, and the mode selector is
set to RUN.
or
• You switch the mode selector on the backup CPU from STOP to RUN.
or
• You POWER ON the backup CPU (mode selector to RUN).
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
Starting SYNCUP
Primary CPU
Commissioning
12.4 Operating and system states
Backup CPU
389