Testing bed heater output on Duet3

mikeabuilder

I'm wiring up my new 3D printer and the bed heater is not working. I've got an AC SSR controlling a silicone heat pad. The thermistor is connected and providing a correct temperature reading. The input (control side) of the SSR is connected to out0 on my board. When I give the bed a temperature target and make it active in the web control, nothing happens for a bit, then I get an error that the heater is not working. The temperature has not changed at all. I know the error is because of lack of heating and I'm trying to find the root cause.

I've measured the DC voltage across the out0 pins and it stays 0. I know it should be doing the PWM thing and I assume the volt meter would give me the average voltage. So I'm assuming that the PWM is not getting turned on properly. I've tried switch the polarity of the wiring to the SSR input - still no joy.

My latest is to disconnect the wires from out0 and try to verify it does something. Of course, I get only a little time before the thermal error happens. So, to my question - is there a gcode to direct out0 to turn on at a specified PWM %? I figure this can let me confirm the output is working.

Other advice also welcome.

The heater setup in my config.g file looks like this:

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0                           ; create bed heater output on out0 and map it to sensor 0
M307 H0 B0 S1.00                             ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0                                      ; map heated bed to heater 0
M143 H0 S80                                 ; set temperature limit for heater 0 to 80C

M308 S1 P"temp1" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1                           ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 B0 S1.00                             ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                 ; set temperature limit for heater 1 to 280C

My other planned debug step is to switch the SSR input to out2.

Stephen6309

@mikeabuilder Which board? For the Duet 3 6HC you must supply power to the OUT_0 Power in connections.

mikeabuilder

@Stephen6309 - Thanks! SOLVED