Temperature Monitoring and Event Trigger

[wcj97]

Hello all,

So my large format machine has an externally controlled Keenovo heating element. The controller and relay are controlled independently of my Duet. I'm curious if it's possible to monitor the temperature of the bed with the Duet, even though it has no control over temperature. I'd like to be able to set a temperature on the heater controller, and start a print, and have the Duet wait to start the print until the bed heater reaches a certain temp. My bed is large enough that when it heats up it warps a bit, and if the printer starts before the bed is up to temp it can mess up the mesh-bed leveling process. I want to be able to set my bed temp, start a print, and walk away without having to wait for the bed to reach temp before starting the print.

Would an M190 command work for this? I wasn't sure if there needed to be an associated heater or not.

[Stephen6309]

@wcj97 If you configure the duet that there is a thermister on T0 and connect a bed thermister to it, it should work with M190. You'll need to add an additional thermister for the Duet.

[dc42]

You can monitor the temperature and display it in DWC, by using an additional thermistor and creating a virtual heater for it using the M305 command. There is currently no mechanism to wait for a particular temperature to be reached where the Duet does not control the heater; but when we implement conditional GCode commands, it will probably be possible.

Is there a reason why you don't want to use the Duet to control the temperature? One possibility is to use an SSR to switch the power to your heater. You may be able to use the external temperature controller as a safety cutout.

[wcj97]

@dc42 I would use the Duet to control the temperature, but the heating element was purchased pre-wired and I'd prefer not to cut any cables for now.

When you say "virtual heater", do you mean configuring a new heater in the firmware but just not having an actual heating element wired to the duet?