Rockwell Automation 284E ArmorStart with EtherNet/IP - User Manual - Manual (Page 328)

328 Rockwell Automation Publication 280E-UM001B-EN-P – July 2012
Appendix D PID Setup
• The Desired System Pressure set point is maintained as valves in the system
are opened and closed causing changes in flow.
• When the PID Control Loop is disabled, the Commanded Speed is the
Ramped Speed Reference.
Trim Control
In Trim Control, the PID Output is added to the Speed Reference. In Trim
mode, the output of the PID loop bypasses the accel/decel ramp as shown. Trim
Control is used when Parameter 232 (PID Ref Sel) is set to Option 5, 6, 7, or 8.
Example
• In a winder application, the PID Reference equals the Equilibrium set
point.
• The Dancer Pot signal provides PID Feedback to the drive. Fluctuations in
tension result in a PID Error value.
• The Master Speed Reference sets the wind/unwind speed.
• As tension increases or decreases during winding, the Speed Reference
is trimmed to compensate. Tension is maintained near the Equilibrium
set point.
Pump
PID Feedback =
Pressure Transducer Signal
PID Reference =
Desired System Pressure
–
+
PID Prop Gain
PID Loop
PID Integ Time
PID Diff Rate
PID Enabled
Speed Ref
PID Fdbk
PID Ref
PID
Error
+
+
+
+
PID
Output
Output
Freq
+
Accel/Decel
Ramp