Bill -
I'll have to answer, just to assure myself you are saved!!
This is probably no help to you - but just a bit of waffle - it might help.
Mach 3 can put out two types of spindle control - PWM (pulse wave modulation) or "Step and Direction" - in both cases, the signal put out by Mach3 has to be converted to a signal your motor controller understands. The choice of system is decided on Config/Ports and Pins/Spindle setup - top centre - motor control. If you tick "Use spindle motor output" you can them tick which system you wish to use.
Mach 3 than puts out the appropriate signals on pins as designated on Config/Ports and Pins/Motor Putputs - at the bottom under spindle (dont forget the port number or you get nothing). In the case of PWM only the "step" pin is used (direction comes out on two other pins under M3 and M4 instruction). If Campbell requires you to use "Step and Direction" then fill in both pin numbers. (Make sure Output is enabled.
That is it for Mach - no other ticks are required.
Coming to the interface with your Spindle Motor, I will describe the PWM first.
PWM is a square wave siganl at a fixed frequency i.e. it is either on "5v" or off "0v". How much of the time it is on or off is determined by the speed you want the spindle to rotate at. In my case this signal (which is on pin 1 in my system) is fed into a Digispeed comverter (Australian - see Digispeed on the net) which changes the signal into a voltage (between 0 - 10 v) which is fed to the VFD. On my system the VFD supplies a 0v and a 10v wire to the Digispeed, and the return wire gives the corresponding voltage signal back.
On the Campbell board (I have just looked at the PDF) he has gone for "step and dir" system of control - and I think I have found an error in his instructions.
You have ticked the box "Use Motor Control" which is fine - and, I assume, you have set up pins 1 and 14 correctly on the Motor Outputs page.
What you DO NOT need to do is untick "disable spindle relays" and enter into the M3 and M4 boxes "output #1" and subsequently allocate output 1 to a pin number on the Outputs page.
As far as I understand it, if you enter pin numbers on the Motor Outputs page that is all you need. The direction signal will come out of pin 14. You do not need to repeat that - indeed it is counter productive, because, as far as I can see, both M3 (clockwise signal) and M4 (CCW signal) are allocated to the same pin - so you will get the same signal regardless of which direction you wish to motor to go. Try it with "Disable spindle relays" ticked and then test what signals are coming out of pin 1 (you can test this with a volt meter) (if you have access to pin 1 on the break out board) and pin 14. Pin 14 should change from +5v to 0v (or vica versa) when you select M3 or M4. If you have the speed of one of your spindles set to 1000 rpm, and then type S1000 M3 in the MD! line, you should see 5v appear on both pins. (You might see less on pin1). If you type in M4, pin 14 should change voltage. If you type in M5 both should go to 0v.
I do not then understand what Campbell does with the outputs to your VFD. On mine there is a speed signal (0 - 10v) which I have already dealt with. There are then two seperate inputs (four wires - in two pairs). If a pair is connected (using a relay) I get M3, if the other pair is connected I get M4. If neither are connected I get nothing, BUT if both are connected I get an error since both M3 and M4 cannot (and must not) be signalled together to a VFD.
I could go rambling on, but I think I have said enough at the minute - come back if you don't get it fixed.