From what I grasp (and it isn't much
) USB port is rubbish for the type of data transmission needed for motion control. For these USB boards to work they need to
BE the control and in that situation USB is fine. The information they cue up from the motion planner (Mach, Kmotion, whatever) only needs to be transmitted reliably
enough, the 'black box' takes care of the time critical stuff.
Maybe linuxcnc is built in a way that makes accommodating these USB boards difficult. The planner and the control could be inseparable ?
Or maybe no developer with the skills has an interest in this path.
In any case it's starting to look like linuxcnc (emc2) won't be a solution for the raspberry pi any time real soon.
Just my two cents based on nothing but some reading.
.