Digital I/O

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Unable to write to parallel port

I'm trying to control a CNC mill with labview. Currently I'm controlling it using Mach3, which uses data pins 2, 4 and 8 for speed control and pins 3, 5 and 9 for direction control. Because I only want to control the Z-axis, I only need to concern myself with pin8 and pin 9 (direction).

To send pulses through the parallel port, I'm using the example VI "Parallel Port Read and Write Loop VI".  When I control my CNC with Mach3 software, I see the status of the parallel port changing, so reading values from the parallel works ('In' is working)

Does this mean that 'Out' should be working as well? Because when I try to write a boolean value using the VI (for example: all data pins set to high), the values in Register data read all return a low value. What could be the problem here? Someone's got any idea?


I already found a VI which controls a stepper motor through the parallel port (which also uses the Out, but this is also unresponsive.


Btw I'm using windows XP and Labview 2010



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