Artisan - PID control - setting

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
Knightey-

#1: Post by Knightey- »

Hello all,

I tried to roast on my machine Kuban Supreme with the PID control.
My main target is to use this PID feature for the pre-heating of the machine because it takes about 70-80 minutes.

So in my background, there is a profile that I want to follow. When I turn ON the PID control, it starts to working and the slider on the left side of the picture the SV is moving according to the background. This is OKAY and seems to work well.
But the machine does not adjust the GAS according to this SV slider.

So if the BT is the same as SV temperature, then the GAS is OFF by the PLC. Once the BT drops below the SV temperature, the GAS is ignited back, and again it follows the curve.

But the machine should only adjust the GAS setting with PID parameters and not shut off the GAS completely (this is a safety feature, not for controlling the roast curve).

Here in the picture, you can see the background and the real-time profile and what was it doing.
The GAS and AIR are on 50% setup by me at the beginning of the process.



I really don't know what is the "damper" on one of the sliders on the left side beside the SV slider.

Thank you for your help and explanation, what is wrong adjusted in the Artisan SW.

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aabud

#2: Post by aabud »

Not sure if this'll help given the difference in the set ups, but when I had a servo controlling my gas knob via Artisan (no air capability), I had:

Target... Positive: Burner Negative: None
Duty... Steps: 4% Max: 100% Min: 0

From my memory... the way I kept the gas from being shut off completely was to use Event config, Sliders tab to set up an offset (e.g. minimum value)

Here's some screen shots:

Kaldi Home and Artisan Software PID

User avatar
MaKoMo

#3: Post by MaKoMo »

Untick "Invert Control", choose the empty entry for the Negative target. Set Min Duty to the lowest burner value you want the PID to choose, anything above 0% which turns your burner off, like 5%.

Knightey- (original poster)

#4: Post by Knightey- (original poster) »

To aabud:
Hi, I like the way, how you added the PID duty data into a graph.
Is it valid for whole machines?


To MaKoMo,
thank you, this makes sense to me!
So maybe the PID does the change correctly but with the wrong "Duty setting"?
I am going to test in during the weekend roasting.

Knightey- (original poster)

#5: Post by Knightey- (original poster) »

MaKoMo wrote:Untick "Invert Control", choose the empty entry for the Negative target. Set Min Duty to the lowest burner value you want the PID to choose, anything above 0% which turns your burner off, like 5%.
Hello, so this above didn't help really.
Still, the machine works like digital - 1 (GAS value taken from the slider) or 0 (shut off GAS completely).


I found also another S7 setting for PID in PORT setting. This is only for the information.


Without access to the PLC I have no chance to say if this setting is okay or it doesn't.

User avatar
MaKoMo

#6: Post by MaKoMo »

With this configuration, the Artisan PID is sending the SV to the external PID and the Artisan internal software PID is not in use at all. Set the SV entry under PID in the S7 tab to 0, and also the DB# to 0 (instead of those 94) as well as choose the empty entry for Area here. Then Artisan will not contact the external PID but uses its internal software PID instead. Note that you might still want to have some kd value here maybe 5 or even more.

Knightey- (original poster)

#7: Post by Knightey- (original poster) »

Hello MaKoMo:

thank you again for the advice.
I am going to try it on the weekend again.

It is strange, that the setting directly loaded for this roaster machine does not work.

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Knightey- (original poster)

#8: Post by Knightey- (original poster) »

Hello MakoMo,

today I had a chance to test the setting which you wrote me.
So I set up this in the Config->Port->S7:


With this change in S7 table, I was not able to ignite the machine.
I think that it has something to do with SV slider.
Before this change when I turn on the machine and Artisan SW, I had to adjust manually the SV slider for 250°C (or some higher temperature then the BT). Only in this case, I was able to ignite the GAS.

I recognize, that it has an influence on PID Control and there are two more parameters that can be changed:


But some positive change is, that I can see values on SV and DUTY LCD on the right side in Artisan SW.
When I "START" the roast and PID Control, I can see that GAS slider goes UP to 100% and also SV slider up to 250°C.
Only the SV slider do not send the signal into the PLC and the machine did not allow it to ignite.

Any possibility to setup in Artisan to make it work?

User avatar
MaKoMo

#9: Post by MaKoMo »

What you report makes me think that the register the SV slider originally was writing too is actually not to the "Set Value" (target temperature) of the machine, but to set a maximum bean temperature limit. Once the BT rises above that value the machine shuts off the burner for safety. Therefore the machine turns off the burner once you moved the SV slider below the current BT temperature (or just to zero).

I'd like to suggest to put an action on the ON button that sends out an initial value to set this temperature limit to 250C. Select "S7 Command" in the action popup of the ON button (menu Config >> Events, first tab) and put the following in the action field next to that popup. See the screenshot.
setDBint(94,40,250)



[quoteI recognize, that it has an influence on PID Control and there are two more parameters that can be changed:
[/quote]

This "P on Error" vs "P on Input" just configures the PID algorithm to be computed in one or the other way. You need to Google the exact (very technical) difference. I suggest to leave it as is on "P on Error", the default.
But some positive change is, that I can see values on SV and DUTY LCD on the right side in Artisan SW.
When I "START" the roast and PID Control, I can see that GAS slider goes UP to 100% and also SV slider up to 250°C.
Only the SV slider do not send the signal into the PLC and the machine did not allow it to ignite.
This is just because now the SV/DUTY readings are taken from the internal PID, while your initial configuration assumed to operate an external PID in the machine (which might not even exist). In that case, you would need to instruct Artisan to fetch those readings separately from the machine if they are accessible at all.

Knightey- (original poster)

#10: Post by Knightey- (original poster) »

Hello MaKomo again,

wow! This is clever! How do you know it all?

Yes, I have the same meaning as you, that the supplier uses the SV slider only for "emergency" purpose.
It destroyed my coffee a few times in the past during the roast.

So once I press the ON button, then it will send 250°C in the same SV into the PLC as it was with the SV slider.
This could be a working solution and the rest of GAS I can easily operate with the GAS slider as usual.

Maybe I can also add an extra button under the profile with the same setting can not?
Or do you think it is not needed to have it separately?
This is just because now the SV/DUTY readings are taken from the internal PID, while your initial configuration assumed to operate an external PID in the machine (which might not even exist). In that case, you would need to instruct Artisan to fetch those readings separately from the machine if they are accessible at all.
The machine has a semi-automatic roasting implemented on the HMI. There is Siemens KPT 700 touch display on the controller and you can save up to 28 profiles and just follow them by the machines themselves.
To be honest I never tested this function yet, because the 7" LCD is too small for me and I am missing much information there.
So some king of PID it must have inside the PLC, but not working with the Artisan SW.

The supplier wrote to me, the machine wasn't built for following background profile in Artisan SW.