Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 241)

Tune Your Machine
Chapter 10
10-33
In general:
When using this alarm to detect this condition You set the alarm setpoint and Program ladder logic to
Absolute pressure Dangerously high pressure • Well above normal operating level
• Below the level that could result in
machine damage or personal injury
• Stop the QDC module
• Place the machine in a
safe condition
Profile pressure Abnormally high pressure • Just above the highest pressure
expected for the profile of movement
• Low enough to detect problems
• Stop the process
• Signal the operator to take
corrective action
Set the preset of profile watchdog timers after your machine is running
repeatable quality parts. Set it just longer than the repetitive duration of
the subject profile. Use these timers:
as an early alert to operators that a process problem may be developing
in your PLC ladder logic to automatically initiate a corrective action
For example, your PLC-5 processor could monitor the watchdog of the low
pressure close profile and initiate a clamp-action re-try if the watchdog
times out during the profile.
The QDC module uses a proprietary, enhanced control scheme called
Expert Response Compensation (ERC). It compensates for changes in
your machine dynamics, machine hydraulics, raw materials, and other
process variables. It also adjusts the open-loop and closed-loop control
algorithms to compensate for abrupt upsets and long term deviations to
your process. In previous chapters, you ran profiles with the QDC
module’s ERC algorithm disabled.
Use ERC:
to strictly adhere to velocity or pressure (not position) setpoints. For
example, ERC may be of great value during closed-loop LPC control
when actual pressure must not exceed pressure setpoints.
Important: We do not recommend using ERC for clamp control unless
adherence to velocity or pressure setpoints is absolutely required.
Profile Watchdog Timer
Presets
Expert Response
Compensation