Time Behavior - Siemens SIMATIC S7-400H Manual

1. Update aborted
2. Fault-tolerant system remains in Solo mode with existing master CPU in RUN
mode
3. Reason for aborting entered in the diagnostic buffer
4. OB 72 called (with corresponding start information)
The standby CPU then re-evaluates its system data blocks.
Afterwards – but at least one minute later – there is a new attempt at link-up and
update. If unsuccessful after 10 attempts no further attempts will be made. You
must then initiate link-up and update again.
Reasons for expiry of the monitoring times may include:
high interrupt load (i.e. of I/O modules)
high communication load, so that execution of current functions takes longer
in the final phase of the update large volumes of data have to be copied to the
standby CPU.
5.3.1

Time Behavior

Time behavior during link-up
During link-up, the controller in your system should be influenced as little as
possible. Therefore the duration of link-up increases with the rise in the current
loading of your programmable logic controller. Link-up duration depends primarily
on the
communication load
scan cycle time
The following applies to non-loaded programmable logic controllers:
Link-up run time = size of the load and work memories in MB
load
The basic load is a few seconds.
When your programmable logic controller is subjected to a high load, the
memory-dependent share can rise to 1 minute per MB.
S7-400H Programmable Controller Fault-Tolerant Systems
A5E00068197-04
Link-up and Update
1 s + basic
5-17