Hi, again. I hooked up a digital volt meter to the direction pin of X axis of the parallel port on the Intel based computer. When I powered up the computer, the pin went to 3.3V. As soon as I start Mach3, the pin goes to zero volts. I expected it to toggle back and forth when the program runs, but it stays reading 0V the whole time... Pins used are pin 3 is Direction and pin 18 is common.
My setup is configured so that pin 2 is X-axis step, Pin 3 is X-axis Dir., pin4 is Y-axis step, pin 5 is Y-axis direction, etc. Since I twisted the one pair of X-axis motor leads, all three axes are direction active “hi”. All step pins are set active low.
The old PC Chips computer has a NetMos PCI parallel port card on it that I used with an MPG. I decided to check it out. When firing up that computer, the NetMos reads 5.0V on pin 3 until I start Mach3. Then it too goes to 0V. I set all the motor outputs to port 2 and plugged it into the PMDX breakout board. Running the diagonal program X+ Y+ resulted in both axes offsetting -.005”. Running the program with X- and Y- yields perfect return to zero. Yada, yada. It seems that with this parallel port card the polarity of the direction of commanded movement under which the error occurs is reversed from the other computer. The error is still offset to the negative direction as with the other computer, but now it only occurs when the affected axis is starting out in the positive direction. Strange.
I then tried to take the breakout board out of the equation. I have a D-sub 25 male connector that I have used that has 3 separate shielded cables with 4 conductors each. Each cable is wired for an axis so that I can hook it up to a gecko drive directly. Shield goes to earth ground. One wire to com., one to step, and one to direction. As the Geckos are set to +5 volt logic, it should work. Right? Result is no movement at all. I checked everything but for some reason, even the NetMos 5V card doesn't drive the Geckos. Huh? I'm not sure how this TTL stuff works. And yes, I tried reversing the Step and direction settings. No dice.
I plan to hook up the NetMos PP card in the new computer soon, installing the drivers was a pain last time, and then see what effect that has on the symptoms...
Thanks for your help,
Don