Threshold Value Trigger - Siemens ET 200SP Operating Instructions Manual

4.5.7.8

Threshold value trigger

Note
Threshold value trigger: Calculation only after "Analog value preprocessing"
Note that the analog value preprocessing is performed before the check for a configured
threshold value and before calculating the threshold value.
This affects the value that is configured for the threshold value trigger.
Note
No Threshold value trigger if Mean value generation is configured
If mean value generation is configured, no threshold value trigger can be configured for the
analog value event involved.
For the time sequence of the analog value preprocessing refer to the section Analog value
preprocessing (Page 74).
Threshold value trigger
Function
If the process value deviates by the amount of the threshold value, the process value is
saved.
Two methods are used to calculate the threshold value deviation:
● Absolute method
With binary and counter values as well as with analog values with configured mean value
generation, the absolute method is used to calculate the threshold value deviation.
● Integrative method
With analog values without configured mean value generation, the integrating method is
used to calculate the threshold value deviation.
In the integration threshold value calculation, it is not the absolute value of the deviation
of the process value from the last stored value that is evaluated but rather the integrated
deviation.
Absolute method
For each binary value a check is made to determine whether the current (possibly smoothed)
value is outside the threshold value band. The current threshold value band results from the
last saved value and the amount of the configured threshold value:
● Upper limit of the threshold value band: Last saved value + threshold value
● Lower limit of the threshold value band: Last saved value - threshold value
As soon as the process value reaches the upper or lower limit of the threshold value band,
the value is saved. The newly saved value serves as the basis for calculating the new
threshold value band.
CP 1542SP-1, CP 1542SP-1 IRC, CP 1543SP-1
Operating Instructions, 01/2017, C79000-G8976-C426-03
4.5 Telecontrol communication (CP 1542SP-1 IRC)
Configuration and operation
73