Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 74)

Programming
Chapter 3
3Ć31
W30(W50)B15 Error Scaling. (XF) Reset to 0 inhibits loop error
scaling. Set to 1 enables the scaling limits SMIN and SMAX in
words W31(W51) and W32(W52) respectively to determine the
scaled value of the loop error. The scaled or unscaled loop error will
be read by the PC processor in word W62(W69). Refer to section
titled scaling for additional information about scaling.
W30(W50)B14 Decouple. (XF) Reset to 0 inhibits decoupling. Set
to 1 enables decoupling. The loop 1 PID calculation VPID 1 is used
for the feedforward input FFI to the loop 2 control algorithm.
Decoupling overrides the feedforward input FFI for loop 2. (W50
B14 for loop 2 must be reset to 0.) Refer to section titled Closed
Loop Control for additional information about decoupling.
W30(W50)B13 Source of Feedforward Input, FFI. (XF) Reset to
0 selects the value in word W10(W17) as the feedforward input for
the loop. Set to 1 selects the tieback input as the feedforward input.
W30(W50)B12 Feedforward Input Sign. (XF) Reset to 0
maintains the positive value of the feedforward input for the loop.
Set to 1 changes the value to negative.
W30(W50)B11 Feedforward Input Square Root. (XF) Reset to 0
inhibits the square root function. Set to 1 enables the normalized
square root of the feedforward input, (square root of FFI) x (square
root of 4095). Square root allows the linearization of differential
pressure type flow transducers.
W30(W50)B10 Feedforward Term Multiplication. (XF) Reset to
0 inhibits multiplication. Set to 1 enables the feedforward term
(feedforward offset + feedforward input) to be multiplied by the
feedforward gain in word W34(W54). The result is K
F
x (FFO +
FFI).
W30(W50)B07, 06 Feedforward Gain Multiplier. (XF) These
two bits select the multiplier for feedforward gain K
F
in word
W34(W54)(Table 3.F).
W30(W50)B05 Lead/Lag. (XF) Reset to 0 inhibits the lead/lag
function. Set to 1 enables the lead/lag function. The values for the
lead and lag time constants are contained in words W35(W55) and
W36(W56), respectively. Refer to section titled Lead/Lag Filter for
additional information about the lead/lag filter.