1. The ESS (Ethernet Smooth Stepper) control board output on Port 3 is used to supply the PWM signal for laser control as well as the ground. The ESS control board can be found in the Avid control box. 

2. The Opt Lasers-supplied 24 V PSU (Power Supply Unit) connects to an AC source and should be connected 

to the PLH3D-CNC Adapter box to provide the power to the laser head.

3. You can add a breakout board to port 3 to simplify the connection. This is however optional and you can connect directly to the Port 3 pins if you want. 

4. You need to use Pin 3 for the PWM signal and any pin from Pins 18 to 25 for the ground with the provided AVID CNC Router Parts Signal Cable.

5. The set-up shown below utilizes a bigger 24 V PSU unit to power the air control solenoid as well a solid state DC relay. The relays Avid supplies are AC only. The set-up with the added relay ensures the constant airflow through the air assist nozzle. The 24 V PSU is wired to the incoming AC power from the switch.

6. For more details on the ESS port connections and setup, please visit the Warp9 Tech Design's FAQ, then go to the Laser Setup section.  

Laser Setup Section: