Interface for CNCPro, etc.

I am now in my third CNC interface project and find it is still a pain in
the butt to connect all the pieces.

To wit:
1. Galil makes a killer servo board and an equally expensive breakout board
to interface it. Bought both and still had to make an interface to
interface the interfaces.

2. Bought a bolt-on-and-go Microkinetics system. One dead amp, two dead
motors, three bottles of antacid and four thousand dollars later it still
has to be dismantled and rebuilt to fit in a suitable enclosure.
Bolt-on-and-go from Microkinetics is better described as
spend-wait-wait-wait-wait-and-be-dissapointed.

3. Enter CNCPro. Great software that uses the parallel port for step,
direction, I/O and limits. The problem is that a parallel port is not
terminated at the back of the PC with screw terminals. Further, it is not
optoisolated and does not source enough current to drive optocouplers. (You
may or may not agree that optoisolation is necessary. All of the current
motherboards have the printer ports built in. Consider that you will have to
replace a motherboard, possibly memory and CPU if a spike gets in. Now
consider that many of us hobby/experimental types are prone to make the kind
of mistakes that cause this.)

I have a proposal, for which I need your opinions and feedback - maybe even
a little technical expertise.

Suppose I design a card that will fit in one ISA or PCI slot that has
optoisolation, 5V isolated supply for outputs and a screw terminal strip
that sticks out the back for direct connection to amps, switches and aux
I/O. No interface cards to make, no pullup resisters to find a home for, no
breakout boards to buy, no 25 pin DIN connectors or cut-to-length serial
cables to fiddle with. Just connect the amps, switches and I/O to the back
of the PC and go.

I am working on a prototype of this board and plan to build at least a few
of them for my own applications. A little profit from the sale of such
cards would be nice, though that is not my goal, nor will it influence my
decision to do the design. At the very least, the plans could be released
to public domain.

Questions:
1. Do you see enough demand for this kind of board to justify having 50-100
PCB's etched?

2. What functions or features would you add or subtract?

3. Would you prefer a separate (not in the computer) board fed by a 25 pin
cable? This would require an additional cable from the PC power supply to
feed the 5V isolator.

4. I have selected a few candidates for the optocouplers and a shottky
driver to feed them. However, component selection is not my area of
expertise (I'm not sure what is). Can somebody recommend components that
will give a good clean pulse at 100khz? Perhaps a good representative
circuit?


I eagerly await your humble opinions.
Doug Harrison