I was just swirching off all of the equipment when I decided to try using Mach3's Page Up/Down function to move in the Z-axis. I pressed the Page Down button and the spindle moved up! I pressed quickly again to make sure of this and yes, it moved up. I then pressed the Page Up button expecting to move see the spindle move down, but it moved up instead.... It hit the top of the allowable physical range (I dont have limit switches yet) and the reversed direction! (as if to save itself). I tried this a few more times and it seems to happen consistently. At one stage I could not help (no which button I pressed) to stop the spindle (which is switched off and has no tool in it) from bashing into the workpiece in the machine. When this happened, it reversed direction in the same way as hitting the top physical limit.
From my analysis, I feel that there is something not being communictaed to (or the communication is not being accepted by) the recieving end (i.e. the 6040 controller). Gnerally I suspect the direction pin from the computer is not wotking properly or the recieve buffer in the 6040 controller for this line has failed.
I think I will build a simple machine controller from an arduino that will let me test the function of my 6040 controller.This will let me rule out the 6040 controller and suspet the HP server's Paralllel port - I am suspect on this port anyway as it didn't work sufficiently on older Parallel based controllers that I have used util I re-maped the Z axis to other lines on the port.
Any ideas are welcome.