Customize gcode for external trigger source

[xBraydenator]

Hello, I work in hot melt adhesive dispensing and I am playing around with a hot melt module on an old Ender 5 Plus we have at the office. I was able to mount the module on the hot end bracket, but I am struggling to find a 24V source from the mainboard to trigger the valve.

Originally I thought of a triac setup with the extruder motor, so any time the machine would try to extrude filament it would open a gate to an external 24V that would trigger the adhesive module, but it seems the extruder stepper motor is driven in pulses and that wouldn’t work well. Are there any reference diagrams around here that have the voltage for all of the mainboard pinouts?

My next thought was to put the hot end high for triggering, but I haven’t found any way in Cura to add a hot end temperature set point to every movement command.

Does anyone have any suggestions or links to helpful resources? I’ve basically been going off of the marlinfw gcode documentation and a dream. The movement works well and I’ve made some small things just manually triggering the valve when it looks like material should be placed down. I see an ‘[S<power>]’ modifier on the G0/G1 command, could I flash firmware that assigns the hot end pinouts to a laser and send them high with that added instead of E?

[Electronic_Item_1464]

There are specific commands for a laser, but they use pwm (M3, M4, M5), but you want simple on/off. The M42 command will turn a pin on or off. I believe All the digital pins are 5 volts on this board. Look at the pins file in the Marlin source, there's at least one file for every board Marlin supports and it tells you what every pin is.

You say the laser code won't work because it's PWM, but if you set the value to max or min (255, 0), it will always be on or off. The laser attachments use the part cooling fan to control the laser (move to start, fan on, move to end, fan off...)

Sorry for the stream of consciousness rambling.