Parallel port hookup

Discussion in 'The Projects Forum' started by Edmunds, Jun 10, 2014.

  1. Edmunds

    Thread Starter Active Member

    Sep 27, 2010
    Dear friends,

    I have a cnc driver breakout board that takes advantage of 24 of 25 pins on the parallel port. For reasons unknown, pin15 is not connected anywhere. As usual with parallel ports, I'm short of pins to use and the pin15 being an input pin would be especially useful.

    I want to use the pin for a probe input, that basically means a switch. The simplest way I could imagine to achieve that, is just grounding the pin and making the software to detect "Active Low" state. For some (probably good) reason, however, this does not work. I hope I have not burned the pin on the other side with my experimentation, but I seem to be stuck with no more ideas on how to get this working.

    Is there a good guide on how to interface through parallel port somewhere? Maybe somebody has built something similar? Anything.

    Thank you for your time,

    Last edited: Jun 10, 2014
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    Pin #15 is the /error input bit to the Parallel Port Status register.

    To use it, you would need to be able to Read the Status Register. Bit #3

    Last edited: Jun 10, 2014
  3. Edmunds

    Thread Starter Active Member

    Sep 27, 2010
    Thank you for your reply.

    I guess software like Mach3 in my case does that.

    An update to the problem is, the simple solutions I tried before all work. As long as you are connected to right pin to start with :). It was a rather stupid mistake, which I manage to correct now and I can now make it to register Active high and Active low as I please.

    Will try harder before the next "problem post" :).

  4. ScottWang


    Aug 23, 2012