Rockwell Automation T8019 Trusted Process Control Algorithm Software Package - Manual (Page 23)

Trusted
TM
Process Control Algorithms T8019
Issue 8 Sep 07 PD-T8019 23
Parameters PV, R and H must be finite, i.e. not ±infinities or NaNs. Behaviour is not defined for any
other values. If negative values are specified for R or H, their ABS value will be used and the “param”
error counter will be incremented.
The function must record the sample time for the previous input value and calculate the rate of input
value change for the actual elapsed period.
In an overflow condition occurs, the function is to set Q
UP
to PV>0, Q
DOWN
to PV<0 and increment the
“overflow” error counter. In an underflow condition occurs, the function is to set Q
UP
and Q
DOWN
to
FALSE and increment the “underflow” error counter.