Siemens Simatic S7-1500R System Manual page 216

Table 9- 11 Sequence of events: SYNCUP aborts
No. in Primary CPU
dia-
gram
Initial situation: The S7-1500R/H redundant system is in the SYNCUP system state. An error occurs in the backup CPU.
①
The CPU does not switch from the RUN-
Syncup operating state to RUN-Redundant,
but instead returns to RUN and continues to
execute the user program.
Procedure for error correction
1. Eliminate the error.
2. Switch the backup CPU from STOP to RUN.
The backup CPU switches from STOP to the SYNCUP operating state. Synchronization
restarts.
Causes of error and troubleshooting
There are various possible causes of a SYNCUP system state abort. In the event of a
SYNCUP abort, evaluate the diagnostics buffer of the primary and the backup CPU.
Table 9- 12 SYNCUP abort: Causes and solutions
Cause of SYNCUP abort
Too little memory on the SIMATIC memory card of the
backup CPU.
System overload. The user program load is too high, and
the backup CPU is therefore not catching up with program
execution on the primary CPU.
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
System state
SYNCUP → RUN-Solo
Solution
Delete data from the SIMATIC memory card or use a
SIMATIC memory card with greater memory capacity. You
can find more information in the function manual Structure
and use of the CPU memory
(https://support.industry.siemens.com/cs/ww/en/view/59193
101).
Use the "RT_INFO" instruction to generate statistics on the
runtime of OBs, communication or the user program. You
can establish the system load using asynchronous instruc-
tions.
You can shorten the backup CPU delay compared to the
primary CPU by:
Addressing the CPU overload by reducing the post-
•
processing of cyclic events (events from one source, for
example start events for a cyclic interrupt OB).
You can find more information in the Cycle and response
times
(http://support.automation.siemens.com/WW/view/en/59
193558) function manual.
Do not set too low a minimum cycle time for cyclic OBs
•
or increase the minimum cycle time. This reduces the
frequency at which the cyclic OBs are called.
Commissioning
9.4 Operating and system states
Backup CPU
If SYNCUP aborts, the backup
CPU may restart and then
switch to the STOP operating
state. The backup CPU is
ready for a new SYNCUP.
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