I went the simple way and got one of those green power bars that detects load. They also sell them for shop dust collectors. The better ones have a pot to adjust what load triggers the outlet… once the tool comes on, the vacuum comes on automatically.
I use the same lot relay that Jeffeb3 linked to. All I did was wired it up to the first fan pins, and use the M106 and M107 commands to turn it on at the beginning and off at the end. I have both my vacuum and my spindle plugged into it, so they both come on before the cut, and shut off after the job is finished.
Thank you guys, I will consider using fan pins, they are easy to locate and map I guess.
Because I want to understand, how do you identify S pins ? I had a look at Rambo development - RepRap and the board diagrams, but I still can’t relate any endstop S pin to an arduino pin number. What’s the method ?
I can’t use the fans because they are 12V PWM and I need 5V to control my PID.
I tried with Digital pin 45 (PWM) which is 5V PWM. When I look at it on an oscilloscope the low voltage is inconsistent. Do I need to add a pulldown resistor ? Where should I connect GND ?
Hmmm looking at the schema there is a GND on MX2-2 and MX2-5 (pin 45) already has a pulldown resistor. I will test this tomorrow. Hopefully it will solve my problem.