Rockwell Automation 284E ArmorStart with EtherNet/IP - User Manual - Manual (Page 332)

332 Rockwell Automation Publication 280E-UM001B-EN-P – July 2012
Appendix D PID Setup
• If the response is too quick and/or unstable (see Figure 106), decrease
Parameter 234 (PID Prop Gain).
• Typically, Parameter 234 (PID Prop Gain) is set to some value below
the point where the PID begins to go unstable.
2. Adjust the integral gain (leave the proportional gain set as in Step 1). After
a step change in the PID Feedback:
• If the response is too slow (see Figure 107), or the PID Feedback does
not become equal to the PID Reference, decrease Parameter 235 (PID
Integ Time).
• If there is a lot of oscillation in the PID Feedback before settling out
(see Figure 108), increase Parameter 235 (PID Integ Time).
3. At this point, the differential gain may not be needed. However, if after
determining the values for Parameter 234 (PID Prop Gain) and Parameter
235 (PID Integ Time):
• Response is still slow after a step change, increase Parameter 236 (PID
Diff Rate).
• Response is still unstable, decrease Parameter 236 (PID Diff Rate).
The following figures show some typical responses of the PID loop at different
points during adjustment of the PID Gains.
Figure 106 - Response is Unstable
Figure 107 - Slow Response – Over-Damped
PID Feedback
PID Reference
Time
PID Feedback
PID Reference
Time