Test the pins when you are doing nothing, and no programs running, especially not Mach2. Remove the parallel cable from the PC and test the pins at the PC parallel port. Ideally you want all the input/output pins you plan to use to read zero vdc (low) now none will read 0 exactly, you may get some that read 20, 30 milivolts but thats still considered zero. There is a voltage range, I do not know the exact limits but 0 to 1 vdc will most likely be read by the computer as Low zero volt, no signal. 4 to 5vdc will be read as high, it doesn't have to be 5vdc right on the money. But at 3.4 volt you are out here in the middle of lala land and I don't think thats good.
The other suggestion about swapping motors and cables is also a great idea, eliminate some of the other possible causes. |