Rockwell Automation 1771-QDC, D17716.5.93(Passport) PLASTIC MOLDING MODULE - Manual (Page 243)

Tune Your Machine
Chapter 10
10-15
Unselected Valve SetĆoutput Values
We presented guidelines to assist you in determining unselected valve
set-output values (words 09 through 12 in configuration command blocks)
in chapter 7 prior to spanning your machine valves in chapter 9. The value
in these words is the signal level sent to all outputs not selected for control
by the QDC module’s algorithm during a profile.
In chapter 7, you determined the signal output percentages required to
drive the unselected valves during respective profiles. These values should
allow desired ram (screw) control. Although different part set-ups and
other process considerations may require that you modify them during a
particular profile, you should adjust them only if you are unable to obtain
desired closed-loop control by modifying profile gain constants.
Important: When attempting to achieve desired closed-loop control, do
NOT change unselected valve set-output values until after you have
adjusted the profile gain constants.
Important: Large changes to your unselected valve set-output values may
require re-spanning the selected valve for that profile. Refer to chapter 9
for valve spanning procedures.
If you believe your unselected valve set-output values are adversely
affecting your ability to obtain quality closed-loop control, consider the
following:
If your Selected
valve controls:
And you observe: Then:
Pressure Profile segment pressures
substantially greater than
setpoint
Decrease the flow available during the
profile by appropriately modifying the
setĆoutput value driving the flow valve.
Pressure Profile segment pressures
substantially less than
setpoint
Increase the flow available during the profile
by appropriately modifying the setĆoutput
value driving the flow valve.
Velocity Profile segment velocities
substantially greater than
setpoint
Decrease the pressure available during the
profile by appropriately modifying the
setĆoutput value driving the pressure valve.
Velocity Profile segment velocities
substantially less than
setpoint
Increase the flow available during the profile
by appropriately modifying the setĆoutput
value driving the pressure valve.