Verify That My Parallel Port is Working

Updated Nov 24, 2020

I'm having trouble communicating with my parallel port and I want to make sure that it is working. Is there anything I can do to verify its functionality?

Unlike a serial port, there is no loopback type test that can be done. However, there is a way to verify the functionality of each of the data lines. You'll just need 3 pieces of wire to do this. Tie both pins 11 and 12 on your parallel port to ground (any pin between 18 and 25 is a ground pin).  One easy implementation is shown below.

Then open the LabVIEW shipping example called Parallel Port Additional Data Register  This example only works in Windows XP and earlier.  There is currently not a test using Windows Vista or later.  Make sure you enter the correct address value in the IO Register Status Tab. Switch over to the IO Connector Status tab and run the VI. At this point, you should see that pins 2-9 are high (illuminated LEDs). Connect each one of these lines to a ground pin (18-25) and watch the LED go off, indicating that the line has been pulled low.  The light toggling indicates a functional port.

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