Motors never reverse

jblain wrote:

XDir is at 3.38 Volts
XDir @ 0.07 Volts

Any ideas on what is going on here ?

I think you have a 3.3V parallel port, and it has not enough oomph to power the optocoupler on the DIR pin.
(why Step works is a mystery to me, though).

I think you need a different wiring scheme. (and this is the one on my stepper drives, even with a 5V parport).
There is 5V connected to the + of the stepper drive inputs (common on 3 drives, separate on the 4th).
The drives have internal current limiting resistors.
The parallel port either goes to 0V (so current flows, opto turns on) or 5V (or 3.3V in your case) and current stops flowing.
The assumption here is that your parport is high-impedence when "on" (3.3v) and that 5V won't push significant current into it.
I think this is the only way that a 3.3V port can work anyway.
Think as the pins as switches to 0V, not sources of voltage. And bear in mind that it is current flow through the opts which matters.
Asssuming you have Optos in the drives.

See page 5 of this document (actually for my stepper drives) for an example:
www.zappautomation.co.uk/pdf/manuals/PM542%20Manual.pdf

If my theory is correct then the other PC will have 5V on the parport.

However, you haven't told us the make and model of the drives (as far as I can see) nor what (if any) BoB you are using, so don't rewire until we have checked it out.

Break Out Board, used to isolate the parallel port from the drives and sometimes other functions.

John

A "BoB" is a break-out-board. A board with screw-termnals and a D25 connector. Often with isolation and buffering.
It is possible that adding one might be a solution, but that would cost some money.

Looking at the manual, there is no option but to connect the device as I suggested. So that isn't the problem.

If you put your multimeter in current mode between the p-port and the DIR pin it would be interesting to measure the current in both states.
That would answer the question of whether there is always too much current to be "off" or always not enough to be "on".