Hi Neil,

I did something similar for my sous-vide cooker project.

But I ended up using fuzzy logic rather than PID, so my question is: do you=
 really need PID? Also, given you have a fairly controlled environment, may=
be you can tweak the fuzzy logic rather than build auto-tune?

-Marc

On 2011-09-01, at 11:03 AM, PICdude <picdude3@narwani.org> wrote:

> Hi all,
>=20
> I'm going to swap the controller on my reflow oven with something =20
> custom.  It has 3 zones, conveyer, convection and cooling fans.  I =20
> want to do this as simple/quick as possible, but would like to keep =20
> the front panel interface (40x8 LCD, various touch switches, E-stop =20
> and power switch).  There are 3 heating elements each with it's own =20
> solid state relay (3-32V control voltage).  And 3 thermocouples.
>=20
> So I'll have to create my own controller to interface with the front =20
> panel elements and fans/conveyer, but would prefer to find some =20
> off-the-shelf PID temperature controllers, to save me the hassle of =20
> create PID controllers with autotuning.  And it would have to have =20
> some interface that I can control it with my controller.
>=20
> I found some decent candidates at Omega, Factorymation, Automation =20
> Direct, etc, with 3 units running in the ballpark of $220-$270 total.  =20
> I can live with that, but lower cost would be nicer.  These also come =20
> with things I don't need -- UI (LED displays, switches, etc), ability =20
> to do ramps/profiles/etc (I just set to a specific temperature and =20
> regulate).  And they all have RS485/Modbus as the interface, and I'd =20
> have to go figure out that part and code it.  But they have =20
> autotuning, which I really want.
>=20
> So instead, I'm thinking I should be able to find some open-source PIC =20
> (or other uC) PID temperature controller project that I can use for =20
> this.  Building the circuit/PCB/etc is no problem.  Or perhaps =20
> something lower-cost commercial (open-frame for lower cost).  I know =20
> that there is a PID library for the Arduino, but I haven't seen any =20
> autotuning mechanism for it yet, and I think it will take some effort =20
> for me to figure out how to create and autotuning algorithm.
>=20
> Thoughts welcome.  Know of some COTS open-frame type temperature =20
> regulator?  Or a PID temp-control project?  Or perhaps a Modbus master =20
> library for PIC?  Or...?
>=20
> Cheers,
> -Neil
>=20
>=20
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