Location on the board (upper right corner):
Web-UI buttons
In the FluidNC web-based GUI, the buttons labeled “Flood” and “Mist” turn the MOSFETs on/off:
GCode
According to the FluidNC WIki — Supported Gcodes | Wiki.js …
M7 / M7.1 - Mist Coolant
- M7 ; Turns on 2nd MOSFET on right side, VMOT-> GPIO.16
- M7.1 ; Turns off 2nd MOSFET on right side, VMOT-> GPIO.16
M8. / M8.1 - Flood Coolant
- M8 ; turns on 1st MOSFET on left side, VMOT-> GPIO.2
- M8.1 ; turns off 1st MOSFET on left side, VMOT-> GPIO.2