Awesome, I took a quick look around the interwebs and it looks like the newer hottops have direct USB communication support for heater control, and the older ones do a sort of Artisan -> TC4 -> Hottop bunny hop:
http://artisan-roasterscope.blogspot.de/2013/02/controlling-hottop.html
I run it by selecting TC4 in the device selection window and clicking the 'control button' check box. From there, by clicking on the control box in the upper right hand corner of Artisan, I can either enable the SV slider or use the ramp/soak function.
To build this thing I used an old Uno I had lying around, a pair of MAX6675 TC amplifiers (it's an old amp, but I've had them for ages) (
http://www.ebay.com/itm/MAX6675-Mod...924042?hash=item5d517a3d0a:g:DFgAAOSw~1FUVKpW), and a Teledyne SSR (This is all just junk I had lying around in my electronics bins). I'm also going to add an DS18B20 (
http://www.ebay.com/itm/like/111687749572?ul_noapp=true&chn=ps&lpid=82) for ambient temp readings when I have a few minutes.
Layout wise, 1 of the TCs goes into my expansion ring, 1 into the 'floor' of the stir crazy. I gutted my turbo oven, separated the fan and heater functions, and wired the heater to an SSR. At the moment the fan is just 'on' all the time, so I'm pondering wiring the fan to a proportional output SSR and PWM'ing it as an experiment.
The heater SSR is driven by the Arduino, using fast pwm (
https://www.arduino.cc/en/Tutorial/SecretsOfArduinoPWM) + the awesome arudino PID library (
https://github.com/br3ttb/Arduino-PID-Library/).
Again this is all my ghetto-tastic set-up to emulate the very handy TC4 and the Aartisan_QPID sketch which you can use. (
http://www.homeroasters.org/php/forum/viewthread.php?thread_id=3322&getfile=5270)
I'll be happy to clean up my sketch, and post it later this week (it's pre-alpha right now), if anyone is interested in it.
Cheers!