HotTop KN-8828B-2K+ and PID control with Artisan

#1: Post by **trickydick** » March 9th, 2016, 7:57 pm

Howdy,

first post. A little background about my question -

Been home-roasting for about a year on HotTop. I got the "2K" model and then after it came out, the "+" upgrade kit which added a USB port that enabled easy Artisan control. Now I'd like to be able to have PID capabilities, but this is currently not a feature without a separate hardware PID with Artisan.
I brew one "pot" per day (1L water, straight coffee only) and usually do not consume all of it. The HotTop is nice and usually I can crank out two 1/2 pound back to back batches that will get me through the week at my level of consumption. It would be nice to be able to roast a tad more than 1/2 pound though I'm pretty happy at this capacity.
It seems that most people who buy the 2k+ hottop use artisan with either manual operation for logging, or to control the roaster without PID (like me).
Ideally I'd like to try using pre-established curves to make the roaster simply follow them, tweaking manually as needed if that's even possible.

Other than the TC4-HTC combo board and dissecting the roaster to install it all, which sort of bypasses the + upgrade altogether, is there any other option? I've not seen anyone posting on any forum about PID control with the HotTop 2K+. While I am at it, it would also be nice to be able to calibrate the temp probes on the HotTop since there seems to be a different temp when using different computers to control my roaster, which I don't understand. One computer is off by at least 25 degrees F compared to the other, and I don't which is correct!

Thanks!

RH

#2: Post by **happycat** » March 9th, 2016, 10:30 pm

Try homeroasters.org

#3: Post by **slickrock** » March 9th, 2016, 11:19 pm

If you want to use something like having Artisan automatically drive roaster control to follow a background roast profile with continuously varying Set Value (SV), then yes, you will need to go the Arduino-TC4/TC4C route. The good news is the that the TC4/TC4C was effectively designed with electrical element roasters in mind. There is an Arduino Sketch that exists specifically to control the Hottop that allows setting the duty cycle of the TC4 to drive the heating element and fan from within Artisan, but how much that is integrated for background profile tracing in Artisan (i.e. PID control), I'm less certain of. Consider it a project - it is not for the technical faint-of-heart, but is quite rewarding when you get it working.

March 10th, 2016, 12:44 am

With the TC4 setup, there is support in Artisan to track a background curve as you intend to do. But don't expect this to work as well as on a pure hot-air based roaster like the one of [anonymized] in the link below. His roaster reacts a lot faster to changes in burner settings than a hottop.

http://kostverlorenvaart.blogspot.de/20 ... sting.html

Regarding your setup, the Hottop 2k+ (and having both setups next to each other here to compare): I personally wouldn't change your 2k+ into a TC4, with its PID feature the essential different between the two. The 2k+ is a excellent integrated solution (thus more costly than the TC4 path). I will see in the near future if a software PID on the Artisan side could be as effective on controlling the 2k+ as the TC4/PID. I just have to find the time for this little project...

M