Siemens Simatic S7-1500R System Manual page 214

Effects of the SYNCUP system state
SYNCUP has different effects on user program execution and communication functions. The
effects are set out in the table below.
Table 9- 10 Properties of SYNCUP
Procedure
Processing of the user program on the
primary CPU
Deleting, loading, generating and com-
pressing blocks
Processing communication functions
PG/PC operation
Test and commissioning functions, for
example "Monitor and modify tags",
"Monitoring (on/off)".
Connection handling in the primary CPU
Connection handling in the backup CPU
Diagnostics alarms
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
Effects during the SYNCUP system state
All priority classes (OBs) are processed. Processing is delayed during the
snapshot. After the snapshot, the primary CPU immediately resumes user
program execution and asynchronous instructions are started.
Blocks cannot be deleted, loaded, generated or compressed.
The execution of parts of functions is limited and delayed. The system makes
up the delays in all functions after SYNCUP.
Depending on the SYNCUP phase, online connections from the PG/PC to the
CPU may not be possible.
Depending on the SYNCUP phase, no test and commissioning functions may
be possible.
All communication connections are initially aborted.
After the snapshot, the primary CPU sets up communication connections again
with active connection establishment.
The CPU sets up connection endpoints for communication connections with
passive connection establishment.
All communication connections are initially aborted.
The backup CPU establishes connections (ARs) to the IO devices in the
PROFINET ring.
The communication connections on the backup CPU become available during
the backup CPU catch-up process.
Diagnostic alarms can be delayed during the SYNCUP system state.
If diagnostic alarms occur during the "Making up backup CPU lag" phase, the
diagnostic alarms can prolong this phase. You can find additional information in
the section Basics to the Program processing (Page 153).
Commissioning
9.4 Operating and system states
213