Allen-Bradley 22C-B012N103, User Manual

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164 Rockwell Automation Publication 22C-UM001J-EN-E - January 2017
Appendix D Application Notes
– If there is a lot of oscillation in the PID Feedback before settling out
(see Figure 39 ), increase A155 [PID Integ Time].
3. At this point, the differential gain may not be needed. However, if after
determining the values for A154 [PID Prop Gain] and A155 [PID Integ
Time]:
– Response is still slow after a step change, increase
A156 [PID Diff
Rate].
– Response is still unstable, decrease A156 [PID Diff Rate].
The following figures show some typical responses of the PID loop at different
points during adjustment of the PID Gains.
Figure 37 - Unstable
Figure 38 - Slow Response – Over Damped
Figure 39 - Oscillation – Under Damped
PID Feedback
PID Reference
Time
PID Feedback
PID Reference
Time
PID Feedback
PID Reference
Time