Rockwell Automation 1771-QDC, D17716.5.85(Passport) MNL. PLASTIC MOLDING MODULE - Manual (Page 149)

Tune Your Machine for Producing Parts
Chapter 10
10-3
Use the highest possible P and I gain constants for repeatable
performance without hammering your hydraulics
First tune your proportional gain. Then add integral gain.
Typically, the integral term will be larger than the proportional term. The
QDC module’s pressure algorithm differs from classic PID algorithms.
Use an oscilloscope, if available. You can tune loops faster and easier
with it connected to QDC module’s output driving the selected valve.
Important: If you have an oscilloscope, skip to the section Tune Pressure
Loops with an Oscilloscope.
Tune pressure loops without an oscilloscope
Before you begin tuning PID pressure loops, confirm that you:
selected the pressure vs. position (or time) algorithm
selected closed-loop control
zeroed the integral and derivative terms
did not change the proportional term that you entered in chapter 7
disabled
ERC
reset ERC values
disabled
ramping
downloaded all setpoint changes to the QDC module
1. Enter an operational profile representative of the characteristics you
desire for your production cycle.
2. Run several cycles of the profile while comparing profile actuals
(returned in the corresponding status block) with profile setpoints.
Also look for abnormal flexing or pulsing of hydraulic hoses leading
to the controlled cylinder.
If: Then:
Observed actuals are consistently well below
profile setpoints
Increase the proportional term
Observed actuals are consistently well above
profile setpoints
Decrease the proportional term
Excessive hammering and vibration is
observed in the cylinder's hydraulic lines
Decrease the proportional term
Important: Each time you change a gain constant, you must download the
change to the QDC module. Refer to the download procedure in chapter 4.
3. Re-run the profile after each change to the proportional term until
actuals are close to setpoints, and there is no hammering and
vibration in hydraulic lines to the controlled cylinder.