Rockwell Automation 1771-QDC, D17716.5.93(Passport) PLASTIC MOLDING MODULE - Manual (Page 263)

Tune Your Machine
Chapter 10
10-35
ERC is not required for repeatable clamp or ejector positioning. Without
ERC, the QDC module will still force the clamp or ejector to overshoot by
a constant repeatable amount (relative to cylinder speed and QDC
module’s 2 ms scan time).
Do NOT use ERC when:
spanning your valves
using velocity feedforward gain
using profile ramp rates to smooth the operation.
you have NOT tuned the machine in closed-loop control
ATTENTION: Jerky, abrupt clamp motion may result if you
apply ERC to a control loop that has not been properly tuned.
ERC Minimum Percentage Values
If using ERC, adjust values recommended in chapter 7 as follows:
If ERC is enabled (on) and: Then:
The actual velocity or pressure swings wildly
around the setpoint from cycle to cycle
Decrease the ERC minimum % value
The actual velocity or pressure takes several
cycles to achieve the desired setpoint
Increase the ERC minimum % value