Time Response; Determining The Monitoring Times - Siemens SIMATIC CPU 410 System Manual

8.3.1

Time response

Time response during link-up
The influence of link-up operations on your plant's control system should be kept to an
absolute minimum. The current load on your automation system is therefore a decisive factor
in the increase of link-up times. The time required for link-up is in particular determined by
● the communication load
● the cycle time
Link-up takes about 2 minutes for automation systems without load.
It can take more than one hour when there is a high load on your automation system.
Time response during updating
The transmission time during updating depends on the current changes of the process
values and the communication load.
As a simple approximation, we can interpret the maximum inhibit time to be configured for
priority classes > 15 as a function of the data volume in the work memory. The volume of
code in the work memory is irrelevant.
8.3.2

Determining the monitoring times

Calculation using STEP 7 or formulas
STEP 7 automatically calculates the monitoring times listed below for each new
configuration. You can also calculate these times using the formulas and procedures
described below. They are equivalent to the formulas provided in STEP 7.
● Maximum cycle time extension
● Maximum communication delay
● Maximum inhibit time for priority classes
● Minimum I/O retention time
You can also start automatic calculation of monitoring times with Properties CPU > H
Parameters in HW Config.
Monitoring time accuracy
Note
The monitoring times determined by STEP 7 or by using formulas merely represent
recommended values.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
Link-up and update
8.3 Time monitoring
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