PID controller use

[prrriiide]

I recently upgraded to a HERMs system (modeled after this system). Everything works great, but I need some pointers on the PID control.

I understand the proportional; that tells me what the system situation is, i>e. what my temp and set-points are.

I'm hoping to tune this thing to reduce ramp times and amount of overshoot. So I'd like to get some information on how to determine what the settings need to be for the I and the D.

It's the TA4 PID that you can get just about anywhere you can get a controller, and the instructions are in flawless Engrish, so no much help.

Thanks!

 

[danb35]

PID controllers are used in a lot of applications, and most of them have an auto-tune mode that will come up with some decent settings. If you want to do it manually, though, this document discusses a strategy:
http://freshmealssolutions.com/downloads/PID-tuning-guide_R2_V006.pdf

 

[prrriiide]

I'd like to use the auto-tune, but the Engrish instructions were sufficiently vague that I'm not sure how that works. Maybe I'll post the exact wording at some point. It's worth the chortle.

Do you just put it in auto-tune mode and it learns the system? Then what? When do you tell it to quit auto-tuning, and how do you tell it to stop? How does it know when it has surpassed my desired parameters?

Dammit Jim! I'm a brewer, not a logistician!

 

[danb35]

On some other PIDs, you'd get your system set up the way it will be in use--any insulation you'll be using, the same amount of water, etc. Then set a temperature and engage auto-tune. The controller will heat to the specified temperature, probably overshoot, do some calculations, and ultimately come out of auto-tune mode on its own. There usually seems to be an indicator that it's in auto-tune mode--a light flashes or something.

I'm speaking generally, as I'm not at all familiar with the model you're using. Looking around, though, it looks like you'd set auto-tune mode by holding down the blue button for a few seconds until the AT LED starts flashing. Then let it do its thing, until the LED stops flashing, at which point it's tuned.