Connecting a Pump or other accessory to the GRBL-AIO Coolant Output.
Notes:
The coolant output is for switching low voltage & low current DC circuits.
You should be switching a relay if possible rather than powering your accessory via Coolant Pins 2 & 3.
On occasions where your accessory requires less than a few amps then you may power it directly without a relay.
You should connect the DC +ve to both pins 3 & 4 as shown in the circuit diagrams below.
The Coolant control pin that is switched by the AIO is the GND which is on Pin 2.
Your Circuit.
Your relay should have a constant connection to the +VE of the power supply.
Its negative connection should be connected to Pin 2 on the Coolant Output port of the AIO. It is this GND side of your relay’s coil that it’s going to be switched on by the AIO.
GCode Control of Output
M7 – turn mist coolant on. (Not used unless you have specifically reprogrammed the board)
M8 – turn flood coolant on. (Shorts Pin 2 to GND)
M9 – turn both M7 and M8 off. ( Pin 2 disconnected from the ground)
