PID Temperature swing and range

[black88iroc]

I have a JLD612 ran to a k type thermocoupler. I have ran the autotune several times and am still having an issue. The SV is set at 400 and I need it to stay within 398-402 degrees. The controller does fine starting from cold. It starts to get really slow heating up around 385 like it is short cycling the element. The main issue is when the door is opened to check temps or add more parts the PV drops to about 360-370. On its way back to 400 it will overshoot to about 410. It is also cycling the whole time and not on constant. I can't understand why the PID continues to cycle the element after the SV. Is there a setting I can adjust to fine tune this. I have messed with the SouF but it like I said before the oven works fine from a cold start.

1) Is there anyway to speed up the last 15 degrees and keep it from short cycling. I have a contactor and have adjusted the ot to 30 and it doesn't make a difference?

2) Is there anyway to keep the PID from cycling after it has reached SV. I can understand 401 or 402 as maintenance cycles but at 410 it shouldn't be cycling?

3) OutY is set to 1. Does the AH1 and AL1 have anything to do with the temp range or swing?

[glassguy213]

Did you run Autotune (AT)? If so did you do it during normal start up from cold? When you open the door to add parts you are introducing another variable (sudden temp drop) which would not be included in the AT cycle if you did AT from cold start. Your controller can't tell the difference between normal temp drops (when heat is off) and big drop due to door open. So it will ramp back the same (intermittent on) no matter what conditions if under AT control.
The shortcoming of AT is that is looks at the "normal" response of your system to determine the auto settings. Opening the door is not part of the "normal" cycle. You may have to do your settings manually to get what you want.

If overshooting then INCREASE Souf value a little at a time until you get it where you want it.

You are using Outy as 1 so you are using a contact relay? If you have a SSR you should be using outy=2.

[jgsharp]

This isn't related to your problem, but I noticed that you were using the 110V contact relay output. I've been having issues achieving that output. I have SV set to 75, AH1 = 48 C, AL1 = 85 C, AH2 = 40 C, and AL2 = 45 (though the manual says that SV, AH2, and AL2 aren't used when outY is set to '1'. How did you get your controller to energize the 110V output?

Thanks for your help.
Josh

[Tech_Marco]

Are you using it for cooling system? If not , you need to reverse the AH and AL value
If indeed you're dealing with cooling system, make sure to set R=1 (cooling) while R=0 is default for heating.

Marco