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Homeroasters.org » THE ART OF ROASTING COFFEE » Roasting Coffee
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How to use Artisan PID function with custom controller?
JamesR
Hi all, I'm trying to set up Artisan 1.0.0 to control my roast profile. I have read all the documentation I can find, but no one seems to be in my situation.

I am using a modified popper (for now...) coupled with a Yocto-thermocouple device for temperature measurement. For control, I've got a custom Arduino sketch running on an Uno, switching an SSR. My interface to the Arduino is via a basic python script I wrote, which connects via RS-232.

I can use the Power slider in Artisan to control the Arduino, but I can't seem to figure out how to set up automatic control. I feel like I'm just missing some fundamental connection somewhere in Artisan, perhaps in the PID Control dialog.

i.imgur.com/eBz2aNb.png

I've seen some posts on doing this with a TC4, but not with a custom setup.

Thanks in advance,
James
 
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MaKoMo
The new PID control is not yet well documented and still under development. Your setting looks good. As such, the PID takes the input from the BT signal, the set value (in the limits from 149 to 249C) from the background profile (you need to load one of course) and controls the "Power" slider. You need of course turn the PID "ON" by pressing the "ON" button.
 
BenKeith
Will it even interface with his to control it?
I know he says he is using the Arduino UNO but don't know anything about his PID device. I also don't use Artisan so I don't know squat about it, but most using the Arduino are doing it with the TC4. He may be running into a script problem that's not letting Artisan control his.

If you do hit the brick wall with it, there is also the RoastLogger. I use it because it because Artisan didn't have PID control when I started, plus RL seems to offer more flexibility in your control. Still though, not sure it will communicate with your setup.
Edited by BenKeith on 11-03-2016 02:15
 
MaKoMo
The Artisan PID works with everything that can be controlled via Artisan sliders. As he said he can control his maschine via a slider the Artisan PID should work for him.
 
JamesR
BenKeith wrote:

Will it even interface with his to control it?
I know he says he is using the Arduino UNO but don't know anything about his PID device. I also don't use Artisan so I don't know squat about it, but most using the Arduino are doing it with the TC4. He may be running into a script problem that's not letting Artisan control his.

If you do hit the brick wall with it, there is also the RoastLogger. I use it because it because Artisan didn't have PID control when I started, plus RL seems to offer more flexibility in your control. Still though, not sure it will communicate with your setup.


Yeah so my understanding is that there's a software PID in Artisan, as of v1.0.0. So as MaKoMo says, I expect my power slider to move automatically during a roast. If I move my power slider manually, my software does adjust the PWM duty cycle on the arduino as expected.

My heat can be controlled by the Power slider. So if Artisan PID works through that mechanism then I think I've got all the parts in place, I just need to configure them.

I haven't loaded a background profile, I'll give that a try.
 
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firstcrackjack
Was this ever resolved? If so what did you do to get it working?

I'm having a similar issue. I recently got my hands on a TC4 but can't for the life of me get it to control my air popper. I can read the temperature and can control heater power and fan power from Artisan using the sliders in Artisan. Unfortunately, no matter what I do I can't figure out how to get Artisan to automatically control the popper. Manual SV, ramp soak, or background follow modes aren't working.

I've tried everything I can think off. I'm sure I've just overloooking a simple setting somewhere.

Key questions
1) should I use the software PID now available in Artisan or the PID available on the TC4?
2) should I upload aArtisan or aArtisan_PID to the arduino? I tried both.
3) I purchased a zero cross detector. Should I be using it with an air popper? I modified it with separate heater and fan circuits. The heater is approximately a 1000w resistive coil. The fan is an 18v DC motor. It was previously stepped down using one of the heater coils. I'm now stepping down the voltage by using a step down transformer. I tried with and without the ZCD and commented out appropriate lines in user.h file based on if I had the ZCD or not
4) I tried several different settings in the user.h file. Do any other files need to be modified?
5) I only have one thermocouple, BT. I've tested it on Chanel 1 and 2 and made the appropriate changes in user.h and Artisan depending where I had it hooked up.
6) since I've tried a million things I even went so far as to do a clean install of the arduino sketch and Artisan on a second PC and even tried it on a Mac.

No matter what I try I can control the fan speed and heater power using the slider in Artisan. I can not however got Artisan to automatically control the fan or Hester based on a set temperature.

Hopefully I can get this resolved quickly because my stash of roasted coffee is dwindling down quickly and I don't want to rewire this popper to my old manual router control and dimmer box.
 
greencardigan
If you're controlling the fan from AC power stepped down by a transformer then you should be using aArtisanQ_PID with a zero-cross detector so you can do phase angle control of the AC power. aArtisanQ_PID has 4 main configurations set in user.h. You would want the CONFIG_PAC3 mode. But if you already have the heater and fan working properly with the Artisan sliders, then most likely you have the TC4 set up correctly.

If you always plan to be logging with Artisan, I would use the PID functionality built into Artisan rather than the TC4's PID. However, I'm not familiar with the more recent versions of the Artisan software. There should be some info around on how to get the PID active.

You shouldn't have to touch any files other than user.h.

Some possibly useful links:

https://artisan-r...ntrol.html

https://forum.hom...post_62782
Edited by greencardigan on 09-27-2017 13:12
 
greencardigan
And another link

https://www.home-...ml#p531910
 
MaKoMo
There is a flag named "PID Firmware" in the TC4 section of the device assignment of the latest version of Artisan. If ticked Artisan assumes the aArtisan_PID firmware and will send set values (SV) to the TC4 to let the TC4 PID do its trick. If that flag is not ticked Artisan will and the "Control" flag in the device assignment dialog is ticked, Artisan will run the PID algorithm itself. Note that running the PID loop on the TC4 should be more effective as it runs faster. Once that "Control" flag is ticked, there is a blue Control button on the main window that can be used to control the PID (internal or external). There is some information on the Artisan PID in my post: https://artisan-roasterscope.blogspot.de/2016/11/pid-control.html that Brad linked already above.
 
greencardigan
I noticed recently that the using the "PID Firmware" option does not interface correctly with the TC4 in some circumstances (eg using BT on channel 1 and ET on channel 2 while trying to follow the BT from a background roast).

I hope to implement a fix in the Artisan sketches sometime soon. In the meantime it should work fine with ET on channel 1 and BT on channel 2.
 
renatoa
I am now in the situation of OP, i.e. trying to use Artisan PID with other configuration than TC4 or Fuji, to follow a profile.
Using MS6514 USB thermometer as input, and a custom USB-SSR control solution, that works well in manual mode.

The PID logic seems acting erratically, huge oscillations for any PI combination I tried, if you can imagine that the best case was for P = 0.1 and I = 0.1 also...
The input source of PID could be either ET or BT, acts same way.
I don't understand the reasoning of the controller, how can it keep full power on, when the BT is 5 degrees more than SV...

When manual roasting, the sequence was as follows: start at 80% power during charge until ET reach 175C, then lower to 40%, then to 32% when 200C, about minute 3.
Keeping PWM constant at 32% ET has a nice slow ramp to 245C about minute 6-8, and BT/RoR also close to profile within 2C degrees deviation.

So, can anyone succeeded PID follow background with any non-standard custom solution, and can share PID values?
 
greencardigan
Try I = 0. Then the power should be directly proportional to the error (difference between BT and SV). It will be on 100% when x degrees below SV and drop to 0% when BT = SV. The value of x will depend on the value of P.

After you are comfortable with your P value try introducing a small amount of I.

I think that the values of P, I and D should not change when using different hardware (assuming that your sample interval and temperature reading stability remain the same). I have tried using the background follow but only while testing, not for an actual roast.
 
renatoa
Tried with I = 0, no success, even for P = 1.
Coming with BT under the curve, about 5 degrees, Artisan command full power, BT start to raise, at 1 degree difference is still 100%, overshot, 1, 2, 3 degrees still 100%, then at about 8 degrees overshot power is cut with a little modulation between 5 and 8 degrees.
Same when BT is sinking, power is reinstated when 2 degrees under the curve or even later.

Will try to make a clip.
 
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