Commissioning
9.4 Operating and system states
S7-1500R/H redundant system
212
System Manual, 10/2018, A5E41814787-AA
⑤
Making up backup CPU lag
In phase
⑤
, the backup CPU catches up with the primary CPU.
The communication connections on the backup CPU become available during the catch-up
process.
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 overtravel of the backup CPU.
Table 9- 9
Making up backup CPU lag
Primary CPU
Backup CPU
Once the backup CPU has caught up, both CPUs switch to the RUN-Redundant operating
state. Both CPUs process the user program synchronously.
Note
High load during SYNCUP
The higher load during SYNCUP can prolong the program cycle.
If SYNCUP is taking too long and the displays are not showing any progress, you can abort
SYNCUP and optimize your user program. You can find more information under "SYNCUP
system state aborts".
Note
Setting a sufficiently long maximum cycle time
Configure a sufficiently long maximum cycle time for the CPUs. A temporary increase in the
cycle time can occur upon a system state transition SYNCU
P → RUN
-Redundant.
Summary of Contents for Simatic S7-1500H
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