Invert the logic of thermostatic control M106

[Marcelocm1995]

Hi, I have a duet2 wifi with last firmware. I configured thermostatic control for my chamber heater, but I need to turn on fan when heater is on too, and turn off fan when heater turn off.

I have try this "M106 P1 T45 S0.2 H2", but works inverted of I want.

Is there a way to change thislogic?

Thanks.

[dc42]

Can you wire the fan in parallel with the heater (if the heater is powered from VIN), or in parallel with the SSR input (if the heater is AC mains voltage)?

[Marcelocm1995]

@dc42 My heater is AC. I can do this (parrallel with the signal of SSR), but my heater uses bang bang control, I don't want use this metod, besides that my heater has a considerable overshoot.

[dc42]

Why not use PID for the heater? That would also reduce the overshoot.

If you are using RRF3 then you can invert the fan output in the M950 command that sets up the fan port.

[Marcelocm1995]

@dc42 I will try PID. I haven't tried because here in Brazil we can't generate ripple in AC line
(liable to a fine). I'm planning to migrate to RRF3.

[dc42]

@Marcelocm1995 said in Invert the logic of thermostatic control M106:

I haven't tried because here in Brazil we can't generate ripple in AC line

What are the exact regulations? They may be referring to ripple caused by using phase angle controllers. If you use a zero-crossing DC-AC SSR (the most common sort) then the power control is burst-fire not phase-angle.