4-2 Function Mode D Operation •Operation where the control volume is proportional to the variation ratio of the target value Target value Large A074 Large Control volume Small A074 Small •PI operation is the combination of the above P and I operations; PD is P and D operations; PID is P, I and D operations. „ PID Gain Adjustment •If a stable response cannot be obtained in PID function operation, adjust each gain as follows according to the situation. 4 •Feedback value variation is slow when the target value is changed. → Raise P gain. •The feedback value changes fast but isn't stable. → Lower P gain. •The target and feedback values wouldn't match smoothly. → Lower I gain.
•The feedback value fluctuates unstably. → Raise I gain. •Response is slow even with P gain raised. → Raise D gain. •With P gain raised, the feedback value fluctuates and isn't stable. → Lower D gain. Functions „ Excessive Deviation/Output •You can set PID deviation excessive level C044 during PID control. If the PID deviation reaches the PID deviation excessive level (C044), the multi-function output terminal is turned on. •C044 can be set from 0 to 100. The setting corresponds to the range of 0 to the maximum target value. •Allocate 04 (OD) to any of multi-function output terminals P1 and P2 (C021 and C022) or relay output terminals MA and MB (C026).
„ PID Feedback Value Monitor •You can monitor the PID feedback value with d004. •The monitor value is displayed as the multiplied value of the PID scale (A075). "Monitor display" = "Feedback value (%)" Ч "A075 setting" „ PID Integral Reset •Clears the integral value of PID operation. •Allocate 24 (PIDC) to the desired multi-function input. •Clears the integral value every time the PIDC terminal is turned on. Do not turn on the PIDC terminal during PID operation to avoid an overcurrent trip. Turn on the PIDC terminal after turning off PID operation. The integral value is cleared during free running or retry. 4-20