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PID, How do I adjust it? PID Tuning on a ACE PLC

 

Quick Tuning Method

  1. Set I and D to 0, start P high and decrease until oscillation stops
  2. Increase I slowly until the residual error disappears
  3. Add D only if the system consistently overshoots the setpoint

 

 

 

 

P = Proportional (reaction strength)

Multiplies the error between setpoint and actual value. Controls how hard the correction is applied.

P controls the magnitude of the correction applied at any given moment. If the deviation is large, P applies a strong correction. If the deviation is small, P applies a weak correction. Visually, it resembles a ramp, but technically it is a gain-on-error control.

  • Too low → slow, sluggish response.
  • Too high → system oscillates and hunts
  • Start high, decrease until oscillation stops

I = Integral (residual error correction, small fluctuations around the set point)

Accumulates error over time to eliminate the small persistent gap that P alone can’t fix.

  • Too low → system oscillates slowly around setpoint
  • Too high → slow to stabilize
  • Increase gradually to reduce oscilliation arround the setpoint

D — Derivative (anticipation)

Reacts to the speed of the error change. Brakes the correction when the value approaches the setpoint fast, preventing overshoot.

  • Too high → unstable, amplifies signal noise
  • In most industrial applications, leave it at 0