ger21 wrote:I think it might be easier to wire those to the G540 speed control circuit. See the G540 manual.
The G540 has VFD +10v, VFD GND, and VFD OUT terminals which would connect directly to the corresponding terminals (+10V, COM, and AVI, respectively) on the VFD control board. Connect Output 2 on the G540 to the FWD terminal on the VFD control board. I'm hoping you've connected the DB25 port on the G540 to Port 1 on the UC300ETH.
In the UCCNC spindle settings, check the boxes to enable PWM Spindle, and Spindle Relay Output. Under PWM Spindle, set PWM to pin 14, port 1, and set the PWM Frequency to 50hz. Set the PWM Duty to min 0%, max 100%. Under Spindle Relay Output, set the M3 Relay to pin 1, port 1 and check the box for Active Low. Verify that the Use Pulleys box is NOT checked. Set the Spindle Velocity min to 0, max to 24000.
Click Apply Settings, then Save Settings.