Chamber heater issue

[kmart]

Afternoon all,

I recently built another enclosure for my printer with a chamber heater.

Followed this guide:
https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_a_chamber_heater

I have a duet 2 wifi running RRF 3.x
Chamber heater is 120VAC connected to a Crydom D2425, with SSR input connected to expansion connector pins 3(3.3v) and 13(Heater4)

This is the configuration code related to the chamber heater:

M308 S2 P"e1temp" Y"thermistor" T100000 B4725 C7.06e-8  ; configure sensor 2 as thermistor on pin e1temp
M950 H2 C"exp.heater4" T2				; create chamber heater output on heater4 and map it to sensor 2
M307 H2 B0 S1						; disable bang-bang mode for the chamber heater and set PWM limit
M141 H2							; map chamber to heater 2
M143 H2 S50						; set temperature limit for heater to 50C

I had used the thermistor input for e1 not realizing i could also use the e1 heater output to control the SSR that is why i used heater4.

It took a while before i figured out i had to add 'exp' to the M950 command. After i did the heater showed up properly in DWC with temperature readings. Problem is that it appears to be operating in reverse.

When the Duet boots, the SSR is activated so heater is on, even though the firmware reports it off. If i turn it on in DWC, the heater turns off until it enters fault because the temperature is not climbing.

I triple checked all connections, 3.3v pin is going to + input of the SSR and heater4 pin is going to the other. Reversing them makes nothing work at all. If i remove the heater configuration it does not activate on boot.

Any advice?

[kmart]

Managed to answer my own question.

Inverting the heater4 pin solved it.

Thanks

[dc42]

@kmart when using the heater outputs on the Duet 2 expansion bus to control an SSR, it's best to connect the SSR control terminals between +3.3V and the exp.heaterN output, not between the output and ground.

[kmart]

@dc42 sorry if I wasn't clear but that's exactly how I have it connected.

Thank you