pwm schematic help required please?

[Doddy]

The direction is switched via relays on the other board (I assume as they click when direction is programmed), the voltage from the breakout board when I mdi input s240 m4 is 0.5v, then at s500 measures 1.0v, at s1000 2.0v etc etc.

Are you advocating connection of the + PWM lead from the breakout board go to wire 3 and the other pwm to wire 4?

I did say electrics are not my field!

Hmmm, looking at that you might want to take up Italian cooking, to make sense of that spaghetti :). <-- intended with tongue in cheek

Okay, I don't know your BoB - but looks pretty generic. That makes me think that the "outputs" from the controlling PC will be buffered with the two large chips (74HC244s?) - they'll be able to drive the PWM output low enough to activate the opto-isolator, and so *should* work (or at least not blow anything up). Suck it and see. My other comment was thinking that if, and I don't know about this, but if the BoB doesn't output the standard PWM pin out, but instead only provides the resulting analogue drive, then instead of trying to route the standard PWM, use the other outputs that are associated with the typical 4/5 axis drives on the BoB - as these are easily available (and from within Mach its easy to remap the PWM output to any pin).

My conversation about arduinos is simply to take an unknown (mach) out of the equation to help better understand how to drive the speed controller, but I'm presuming - perhaps too much - that that's in your interest/comfort zone. It's nothing to do with CNC but would be a great way to test the board in (almost) isolation.