Transition Description Effects
The CPU that you switch from STOP to RUN first remains/becomes the primary
CPU. It switches to the STARTUP operating state and processes the startup
blocks.
The backup CPU remains in STOP.
Operating state
transition
STOP → STARTUP
After switch-on, the primary CPU switches to the STARTUP operating state if:
• The hardware configuration and program blocks are consistent
and
• You set the CPU to RUN via the PG/PC or the display and the mode selector
is set to RUN
or
• You set the mode switch from STOP to RUN.
DB contents are
retained.
If there is a role change
between primary and
backup CPU, connected
IO devices are temporar
ily unavailable.
④STARTUP → RUN-Solo, STARTUP → RUN
Transition Description Effects
System state trans
ition
STARTUP → RUN-Solo
The redundant system switches from STARTUP to the RUN-Solo system state if:
• The primary CPU has initialized the PLC tags
and
• The primary CPU has executed the startup blocks successfully
and
• "Startup CPU only if compatible" is configured, there is feedback from all IO
devices before the end of the configuration time and all IO devices match
the configured hardware configuration or "Startup CPU even if mismatch" is
configured and the configuration time is up.
The backup CPU remains in STOP.
Operating state
transition
STARTUP → RUN
The primary CPU switches to the RUN operating state if:
• The CPU has initialized the PLC tags;
• The CPU has executed the startup blocks successfully;
and
• "Startup CPU only if compatible" is configured, there is feedback from all IO
devices before the end of the configuration time and all IO devices match
the configured hardware configuration or "Startup CPU even if mismatch" is
configured and the configuration time is up.
The process image is
updated and processing
of the cyclic user pro
gram begins.
The outputs of the IO
devices are initialized.
⑤RUN-Solo → SYNCUP, RUN → RUN-Syncup, STOP → SYNCUP
Transition Description Effects
System state trans
ition
RUN-Solo → SYNCUP See section SYNCUP sys
tem state (Page 270)
285
Commissioning
11.4 Operating and system states
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
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