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Configuration and operation
5.11 STEP 7 configuration of individual parameters
5.11.5.4
Threshold value trigger
The CP calculates the value for the threshold value trigger after the analog value
preprocessing, refer to the section Threshold value trigger and Analog value preprocessing
(Page 48).
Threshold value trigger: How the integrattion calculation works
To calculate the threshold value trigger, the integration method is used.
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 amount of the
integrated deviation.
The calculation cycle
The integration threshold value calculation works with a cyclic comparison of the integrated
current value with the last stored value. The calculation cycle in which the two values are
compared is 500 milliseconds.
(Note: The calculation cycle must not be confused with the scan cycle of the CPU memory
areas).
The deviations of the current process value are totaled in each calculation cycle. The trigger
is set only when the totaled value reaches the configured value of the threshold value trigger
and a new process value is entered in the send buffer.
52
Operating Instructions, 02/2015, C79000-G8976-C384-01
CP 1243-1 PCC
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