Siemens SIMATIC S7-1500 System Manual page 278

Commissioning
11.4 Operating and system states
Procedure
Diagnostics alarms
SYNCUP system state aborts
Abort is possible in a range of cases even if you have successfully launched the SYNCUP
system state:
• If one of the two CPUs POWERS OFF.
• If you switch the backup CPU to STOP; the primary CPU continues operating in RUN
operating state.
The abort of SYNCUP may be delayed by a few seconds.
• If you set the primary CPU to STOP; the redundant system switches to the STOP system
state as the backup CPU was not ready to take over control of the process (not shown in
the following figure). If appropriate. the backup CPU restarts.
• If the backup CPU lag is not reduced to less than the smallest value after 100 program
cycles and 10 to 13 seconds, the primary CPU aborts SYNCUP. Evaluate the diagnostics
buffer of the primary and the backup CPU.
• If one of the CPUs detects an error that impedes progress, for example if the cycle time is
exceeded in the primary CPU.
• If the PROFINET ring was already interrupted before changing to the SYNCUP system state
or if the PROFINET ring is interrupted during SYNCUP.
• If there are other devices in the PROFINET ring apart from the CPUs to which the media
redundancy role "Manager" or "Manager (auto)" was assigned.
• If, in a configuration with PROFINET rings (R1), the backup CPU was assigned the media
redundancy role "Not device in the ring" before the SYNCUP.
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Effects during the SYNCUP system state
Diagnostic alarms can be delayed during the SYNCUP system state. The OB 82
reports delayed diagnostic alarms.
If diagnostic alarms occur during the "Making up backup CPU lag" phase, the dia­
gnostic alarms can prolong this phase. You can find additional information in the
section Basics to the Program processing (Page 220).
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD