Is there a way to use Mach4 to control my VFD?

The best way to determine how to control your VFD using Mach4 is to read the MAch4 manual found here: http://www.machsupport.com/wp-content/uploads/2014/05/Mach4%20Installation%20Manual.pdf You will find that there a a few ways to control the spindle/VFD on your CNC machine or CNC Router. - The first and easiest is to have your VFD's power controlled by a relay. This will allow your spindle to have on/off control through Mach4 with an output pin. - The second is to have a controller output a DAC voltage between 0-10 volts to control speed on the VFD/Spindle. There is a termial on the VFD to receive this signal line. The controller will also have an output that outputs a high or low and that can control the on/off on the VFD. - The third, and more difficult of the three methods is to use a USB to Serial adapter (USB to USART or RS-485). The Computer plugs into the adapter using a USB cable and the adapter uses the RX/TX to connect to the VFD's terminals for communication. This will provide a great amount of control. Mach4 will need a plug-in to make this option work.