I use ExperTune PIDtune to have PID values on a Moore 352. I want to use the Dtime value but in my controller. I also have Dgain. What is the effect of this gain to my algo? Where should I adjust it? Merci for your help.

 

On the Moore 352, Dtime is the true derivative time.Dgain is a factor which adjusts the time constant of a filter on the derivative signal. (The time constant is Dtime/Dgain. 0.0 < Dgain <= 30.0) If Dgain is set to 10, then the filter time constant is 1/10 of the vaue of Dtime. Many manufacturers pre-set Dgain (or its equivalent) to produce a filter time constant of one-tenth the derivative setting. With some manufacturers, this is hard-coded or hard-wired and cannot be changed. With the Moore 352, it is adjustable, if anyone has a good reason to change it. If Dgain is set too large, high frequency noise on the derivative signal is filtered out. If Dgain is set too low, the filter becomes so sluggish that it defeats the purpose of having derivative. In years of controller tuning, whenever the parameter could be adjustable, I have set it to 10 and not worried about it further. That seems to work.

My recommendation: Set Dgain = 10, and let Expertune determine Dtime.