Siemens Simatic S7-1500H - Page 276

The display of the primary CPU indicates the copying progress.
Table 11-9Copying the work memory
Primary CPU Backup CPU
Step 4 of 5
Copying work memory
to Backup PLC.
37%
RUN-Syncup
Syncup...
?
?
6ES7 517-3HP00-0AB0
CPU 1517H-3 PN
CONNECTING...
Overview
OK
The backup CPU is busy accepting the data before it can also process the user program.
⑤ Making up backup CPU lag
In phase ⑤, the backup CPU catches up with the primary CPU.
The backup CPU sends a status message on its program progress to the primary CPU at each
cycle control point.
The display of the primary CPU indicates the lag of the backup CPU.
Table 11-10Making up backup CPU lag
Primary CPU Backup CPU
Step 5 of 5
Minimizing delay
between this PLC
and the Backup PLC.
00:00:07.359
RUN-Syncup
Syncup...
?
?
6ES7 517-3HP00-0AB0
CPU 1517H-3 PN
CONNECTING...
Overview
OK
276
S7-1500R/H redundant system
System Manual, 11/2022, A5E41814787-AD
Commissioning
11.4 Operating and system states