The section in the top right corner of LaserBoard dedicated to controlling an air assist, or potentially any other peripheral that should turn on at the start of the job and off at the end.
It comes from pin 2.4 on the microcontroller. It goes to a level shifter that brings it up to 5v, and then there’s an FET.
The level shifted output is the 2 pin header labeled “5v Air Signal”. This can control a low current 5v (TTL) device such as an external MOSFET module, SSR, or 5v relay.
The on-board FET is accessed via the 2 pin screw terminal labeled “Vin Air Control”. The + is connected to the voltage supply of the board, which, if you’re using the included C3D Power Brick, means 24v. So you can connect a 24v fan, relay, or solenoid to the screw terminal.
We encourage you not to run large loads directly:
The 5v output is only for logic-level signaling with a maximum of 8mA.
The FET output itself can do up to around 500mA – the limit is not the FET itself nor the terminal connector, but rather the fact that the Cohesion3D Power Supply is 4 amps that has to be shared between 4 stepper drivers, the board logic, and the GLCD Screen. That leaves about 500mA for a peripheral that will control your air assist.
LightBurn sends an air assist command for each firmware to turn this on and off.
For Smoothie firmware this revolves around
M106 for On and
M107 for Off.
For GRBL-LPC firmware it is
M8 for On and
M9 for Off.