Parker 590 series, Product Manual

Page: 131 / 242

Programming Your Application
6-41
590 Series DC Digital Converter
I ntegral (INT. TIME CONST.)
The Integral term is used to give zero steady state error between the setpoint and
feedback values of the PID. If the integral is set to a small value, this will cause an
underdamped or unstable control system.
D erivative (DERIVATIVE TC)
This is used to correct for certain types of control loop instability, and therefore
improve response. It is sometimes used when heavy or large inertia rolls are being
controlled. The derivative term has an associated filter to suppress high frequency
signals.
+
Input 1
[410]
Ratio 1
[412]
Divider 1
[418]
Input 2
[411]
Ratio 2
[413]
Divider 2
[414]
F
[403]
D
[401]
I
[402]
P
PID Output
[417]
+
+
+
+
Neg Limit
[406]
Pos limit
[405]
O/P Scaler
(Trim) [407]
PID Error
[415]
Enable
[408]
Integral Defeat
[409]
Reset
Prop
[404]
Pmin
[474]
Dmin Dmax
Mode
[473]
Mode = 0
1
4
Diam*
PID Gain
Profiled Gain
[475]
Gain Profiler
PID Clamped
[416]
0%
* - Linked internally to Diameter Calculator
You should achieve a
critically damped
response, which allows
the mechanics to track as
precisely as possible a
step change on the
setpoint.
Critically Damped Response
Underdamped
Critically damped
Overdamped
Setpoint
Value
Setpoint
Time
Time