From my research (not formal testing) K type has a broader temp range, but is more expensive. K style seemed to be the ubiquitous standard when I was designing data logging, at least in roasting circles, so I went with that one first. Recently, I've been contacted by many shop roasters who are wanting to use data logging with the probes built into their roasters, which are usually the cheaper J type. Alas, I don't own a shop roaster, so until I do I can't speak from experience about the feasibility of mod'ing them, I can only say that if it's a J or K type thermocouple that you can hook up to the Phidgets temp sensor, Roastmaster should be able to handle the input just fine.
Having the iPad wireless and portable comes in very handy. Phidgets give you the freedom to walk about with your iPad and monitor the roast and see live temp updates from other rooms - or the couch or deck or whatever, while the hardware sits dutifully next to the roaster, broadcasting its readings via wifi - much easier than you having to sit by the roaster. The BBQ would not offer that, since the end of the probe is connected to the iPad - you'd be stuck there with it - or at least need to walk in and check it frequently. Again, the BBQ is for a future release. I'm hoping the API works well - I believe it will, but i won't be ready for at least another month.
Why would you need above 500? Hmmm, that's a good question. In an earlier version of Roastmaster, I limited curves to a range of 999 thinking that was plenty of head room. A user contacted me, saying that he needed a greater temp range for larger shop roasters, claiming their roaster needed over 1000. I could only assume that possibly the charge temp for larger batches can get to be pretty high. I've always doubted that, though - if they were that high, then J type probes wouldn't measure them. Possibly, in retrospect, he wasn't understanding something about curves. Whatever the case, I present that info about the temp range just so you'll be aware (or other googlers) in case there's something about the physics of shop roasters the eludes me.
I know that on my Quest, temps never go above 230° C, so a temp range of 500° F would work fine for use with a Quest.
I personally use a Behmor and a Quest both, but Roastmaster is pretty open-ended in its design (almost to a fault in some areas). Folks use it with lots of different roasters - truth be told I talk to more shop roasters than home roasters. I researched all of the major home roaster models when designing it, and settled on a design (particularly of profiles and curves) that I felt would work well with any roaster - even shop roasters. I've payed a lot of attention to the Behmor, due to the popularity of the roaster, but have remained very steadfast in keeping a Behmor workflow as an 'opt-in' scenario. In other words, you won't find any Behmore-specific fields or data, unless you actively enable them. Regretfully, I have to fend off many requests from Behmor users in order to keep the design of profiles and curves simple and flexible.
The SBC3 is
here. If you are planning on purchasing a laptop regardless, then might be best to try data logging with that first to get the hang of it. I've mounted my SBC and temp sensor on a small board, with a hook I hang next to the roaster. THat's much easier IMO, than hauling out a laptop/temp sensor combo every time I roast. Your mileage my vary though. The good thing is you can try it out without investing in the SBC, then add that later if you want to.
Hope this helps
Danny
