Rockwell Automation 1771-QDC, D17716.5.87(Passport) CLAMP AND EJECT MODE - Manual (Page 101)

Load Initial Configuration Values
Chapter 7
7-25
Pressure Algorithm Selection
(FCC02, SCC02, TCC02, LPC02, FOC02, SOC02, TOC02, OSC02, EAC02, ERC02)
When executing pressure vs. position profiles, the QDC module can use
one of two types of PID algorithms: dependent gains (ISA) or independent
gains (Allen-Bradley).
If B07 = : Then it uses:
0 Dependent Gains (ISA)
1 Independent Gains (AĆB)
Dependent gains (ISA):
Output = Kc[(E) + 1/Ti
o
∫ t (E)dt + Td
*
d(E)/dt]
Independent gains (AB):
Output = Kp(E) + Ki
o
∫ t (E)dt + Kd
*
d(E)/dt
Comparison of Gain Constants
Compare standard and independent gains constants as follows:
Dependent Gains Constants: Independent Gains Constants:
Controller Gain Kc (dimensionless) Proportional Gain Kp (dimensionless)
Reset Term 1/Ti (minutes per repeat) Integral Gain Ki (inverse seconds)
Rate Term Td (minutes) Derivative Term Kd (seconds)
Other variables used in any algorithm choice include:
Output = Percentage of full scale
E = Error (scaled) SP-PV (Setpoint-Process Variable)
PV = Process Variable (scaled)
Convert from standard to independent gain constants by substituting
controller gain (Kc), reset (1/Ti), and rate (Td) values in the following;
Kp = Kc unitless
Ki = Kc
60 Ti
inverse seconds
Kd = Kc(Td)60 seconds
We recorded bit 07 = 1 for A-B independent gains on the worksheets.
The closed-loop tuning procedures in chapter 10 assume this selection.
Select the Type of
PID Algorithm