Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 216)

Tune Your Machine
Chapter 10
10-8
5. If you are satisfied with your unselected valve set-output values and
still cannot match velocity actuals to desired setpoints, your control
may require a small feedforward gain.
6. If necessary, slowly increase the feedforward term while running
machine cycles until velocity actuals satisfactorily match entered
setpoints.
Important: If you must use feedforward gain to adequately tune your
velocity profile, do NOT enable ERC for this profile.
Tune Velocity Loops With An Oscilloscope
Before you begin tuning your velocity loop, confirm that you:
selected the velocity vs. position algorithm
selected closed-loop control
zeroed the VelFF term
disabled
ERC
reset ERC values
disabled
ramping
ATTENTION: Verify that you have correctly set the following
words and bits in CPC and OPC that control zone overrun to
guard against damaging the clamp or mold.
CPC03-B11 = 0: Execute low pressure close if zone overrun occurs
set CPC61 to a value larger than normal for a larger mold-protect zone
OPC03-B11 = 0: Execute open slow if zone overrun occurs
set OPC61 to a value smaller than normal for a larger open-slow zone
1. Enter an operational profile representative of characteristics you
desire for your production cycle.
2. Check that you zeroed the profile’s feedforward term. Leave the
proportional term at the value you entered in chapter 7.
3. Downloaded all setpoint changes to the QDC module.
4. Connect an oscilloscope to your selected velocity control valve
5. Run several profile cycles while observing the oscilloscope trace.