Nate89 (Customer) asked a question.
Output hysteresis
I am trying to control recirculation flow rate within a system and the pump I am using has hysteresis within it that I am trying to tune out. I am currently using a solo 4824-LR PID controller.
The pump takes a 0-10VDC signal however when modulating from the "off" state to the "on" state the pump is on standby from 0-2 VDC.
When modulating the pump from the "on" state to the "off" state. The pump will spin at it's minimum speed from 2VDC to 1.5 VDC.
the input signal into the controller does not have any hysteresis associated with it. Is there a way to control the output signal to adjust for output hysteresis?
Wouldn't the Integral term in the PID eventually compensate? Now, "eventually" may not be fast enough, Depending on ones experience one might experiment with manually tuning, though I not sure how far that will get you while still maintaining stability.
"If "pump is on standby from 0-2 VDC." was the only problem and was the same for both starting and stopping, then parameter P1-18 "Analog low adjustment" might help, but with your asymmetrical response I don't know that it will provide much if any benefit in your case.
Other than that I don't know that the SOLO has any other options that would help you. Sounds like you need "fuzzy logic" 😉 or maybe better, a closed loop pump control, but that won't be free.
Assuming one does want to retain the SOLO for the operator interface, and depending on one programing experience, one might consider something like a P1AM and a P1-4ADL2DAL-2 combo Analog I/O module and create a device the sits between the SOLO and the pump and has a lookup table to linearize the response. But that might just be crazy.