Siemens SIMATIC S7-1500 System Manual page 286

Commissioning
11.4 Operating and system states
Transition Description
The primary CPU is in the RUN operating state. The redundant system switches
from the RUN-Solo system state to the SYNCUP system state if:
• You set the backup CPU to RUN via the PG/PC, the display or the RH_CTRL
instruction (Mode 7) 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)
and
• the SYNCUP system state is not disabled by the RH_CTRL instruction.
Operating state RUN → RUN-Syncup
transitions The primary CPU switches from the RUN operating state to the RUN-Syncup
operating state if:
• You set the backup CPU to RUN via the PG/PC 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).
STOP → SYNCUP
The backup CPU switches from the STOP operating state to the SYNCUP operat­
ing state.
⑥
SYNCUP → RUN-Redundant, RUN-Syncup → RUN-Redundant
Transition Description
System state trans­ SYNCUP → RUN-Redundant
ition The redundant system switches from SYNCUP to the RUN-Redundant system
state if SYNCUP has successfully run.
In the RUN-Redundant system state, the two CPUs execute the user program
synchronously.
Note: A temporary increase in the cycle time can occur upon a system
state transition SYNCUP → RUN-Redundant. Configure a sufficiently long
maximum cycle time for the CPUs.
Operating state RUN-Syncup → RUN-Redundant
transitions The primary CPU switches from the RUN-Syncup operating state to the RUN-
Redundant operating state if SYNCUP has successfully run.
SYNCUP → RUN-Redundant
The backup CPU switches from the SYNCUP operating state to the RUN-
Redundant operating state if SYNCUP has successfully run.
286
Effects
See section SYNCUP sys­
tem state (Page 270)
Effects
This system state trans­
ition does not have any
effect on data.
Communication connec­
tions (HMI, PG/PC) on
the backup CPU become
available.
Both CPUs process the
user program synchron­
ously.
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD