Have a 4'x4'x 6.5"Z router. Generic DIY build with aluminum extrusion, steppers. All works well. Have 2.2KW water cooled spindle and VFD. Just baffled by the almost completely confusing wiring info out there between Mach3, BOB and VFD.

Spindle works fine from VFD front panel. Router runs great and homes all axis' fine (gantry is slave Y&A). I can set up and run Gcode fine using the spindle manually.

I have three different breakout boards. One has no relay (currently installed), one has a single relay and says V3 on the board and is 5 axis, the other has 3 relays and says Bv2 on the board.

I think I understand the basic four wire setup with FOR triggering turn on of the spindle, don't need reverse; and VI for 0-10V D-A and the commons. What I don't understand is the specs for and the powering and using of the relay on the board.

Is there some sort of gold standard for the wiring between the BOB with relay which I would like to go to and the standard Ebay VFD?

Some things I have read say use 24v input power to the BOB and then ouput at the relay which I don't understand. Also the 3 relay BOB I have has a PWM pin as well as a 0-10V pin meaning it may output PWM directly for spindle speed control. Seems that would be cleaner than D-A conversion if that's true.

Any help would be appreciated. I can wire and have built machines from scratch but this is just a puzzle. Wish I could just find a wiring diagram and MACH3 setup for the parts I have.

jfk in central VT