PID tuning woes

[drbitboy]

Where do signals fq-100, fq-500 come from?

See Post #69:

so here they are

fq-100 is the flow out of p1
fq-500 is the flow out of p2
lt-100 is t1 level
lt-300 is t2 level
t-1000 is the decant tank ...

Anyway, success.

PV Max values are linear K_p (Assuming PV Min values are 0), so magnitudes can be dropped to bring K_p into whatever range (0-100) is necessary.

To get there, e.g. to 13.5 to 4095, when doing it in one step causes a process upset, it may be necessary to do it in steps e.g. 4095 => 3000 and increase K_p, 3000 => 2250 and increase K_p, etc. Or just put the controller in Manual, make the change, then put it back into Auto.

 

[MaxK]

I have read Post #69. Is this data from flow sensors? Such noisy?

 

[drbitboy]

I have read Post #69. Is this data from flow sensors? Such noisy?

Yes, I have been assuming those are flow sensors. However, the PID output CV is being linearly scaled to be the VFD speed reference, so the flows are interesting but do not matter much.

Yes, they are pretty noisy. I don't know if that noise is from the noisy level through the CV, but it does not seem to be an issue.

 

[MaxK]

Yes, they are pretty noisy. I don't know if that noise is from the noisy level through the CV, but it does not seem to be an issue.

For level or flow control - not, but what about the pump motor?

 

[drbitboy]

For level or flow control - not, but what about the pump motor?

Ooh yeah, that could be.

But the process is so slow that high frequency noise should not matter