Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 217)

Tune Your Machine
Chapter 10
10-9
Ideally for each step of a multi-stepped profile, the oscilloscope trace
should rise or fall quickly to a controlled level and then flatten out.
Bounce or chatter when rising or falling is undesirable.
If: Then:
Your scope trace for any given profile step
never levels off (it is either rising or falling for
the entire step)
Increase the proportional term
Your scope trace for any given profile step
rises (or falls) quickly and then bounces" or
chatters" around a voltage/current
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.
6. Re-run the profile after each change to the proportional term until
oscilloscope traces quickly level off without bounce or chatter.
Important: If you cannot alter the proportional term so that oscilloscope
traces quickly level off without bounce or chatter, verify that your
unselected valve set-output values are correct for your application. (Refer
to chapter 7 and the discussion later in this chapter).
7. If you are satisfied with the unselected valve set-output values and
still cannot make the oscilloscope trace quickly level off without
bounce or chatter, your control may require a small feedforward gain.
8. If necessary, slowly increase the feedforward term while running
machine cycles until the oscilloscope trace levels off without bounce
or chatter.
Important: If you must use feedforward gain to adequately tune your
velocity profile, do NOT enable ERC for this profile.