HomeRoast Digest


Topic: Poppery I PID controller notes (24 lines)
1) From: John Moody
Following the fine work of Mike (just plain) I setup a Poppery I with the
Fuji PXG controller.  I went with the proportional 4-20ma output and drive
the heater with a Watlow DIN-a-mite SCR power controller.  Bean mass
temperature is using a 1/16” diameter thermocouple probe.
Wow, this thing rocks, just like Mike said it would.  Controlling by bean
mass temperature I was concerned about air temperature oscillation, but it
ramps smooth as butter; chalk one up for good autotuning and proportional
heat control.
I have lots more mods to do, but the first three roasts profiles tracked
right on top of the intended profile, so I’m psyched.
If anyone is considering a controller, I verified that the PXG does not need
the RS-485 interface; the included RS-232 interface handles everything that
the “official” RS-485 communications port does.
John


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