Threshold Value Trigger - Siemens CP 1243-8 IRC Operating Instructions Manual

Configuration and operation
4.7 Configuration in STEP 7 Basic
Transmission mode
The transmission mode of a frame is set in the "Trigger" tab of the data point. With the
option, you specify whether messages of events are sent immediately or following a delay:
● Immediate transfer - Spontaneous
The value is transferred immediately.
● Buffered transfer - Conditionally spontaneous
The value is transferred only when one of the following conditions is fulfilled:
– The communications partner queries the station.
– The value of another event with the transmission mode "Spontaneous" is transferred.
4.7.15

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 78).
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.
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Operating Instructions, 06/2015, C79000-G8976-C385-01
CP 1243-8 IRC