View Full Version : Problem with X

06-01-2011, 07:40 PM
When I brought my CNC I also brought a new motherboard, which did not have a LPT port on it so I fitted a PCI-E LPT card, I soon found out I had no X axis, so I used and old PC with a built on LPT, no problems I assumed the problem with the new board was low voltage so I brought a LPT Buffer and re installed the first PC problem guess what same problem, any one come across this before? is it a pin out problem?

06-01-2011, 09:20 PM
Are you sure the port address is correctly assigned! Sometimes, the bios will pick up a strange address.

06-01-2011, 09:33 PM
Yes, its the address that's on resources for lpt

06-01-2011, 10:30 PM
Do the other axis work? If so, sounds like a possible connection problem because you say it works on the old computer. Are you using the same cable from the computer to the breakout board for both computers?

07-01-2011, 07:36 AM
yes Y & Z work fine if i swap leads on the controller X works, same leads, could it be it needs a different pinout for X?

07-01-2011, 02:13 PM
If everything works on the old computer then possibly you have a bad lpt? I am drawing at straws here, but try switching the pinout if you can and see what happens!

Good luck

07-01-2011, 02:53 PM
What other pinouts would control X? is there a device/software that will detect LPT output

07-01-2011, 03:33 PM
Did you setup the pinout in your controller program on the new computer? All of the control programs (Mack, Turbocnc, CncPro, etc) require you to configure the system and tell it which pins to use for the various functions.

Usually "most" people use parallel port pins 2 and 3 for step direction of the X axis. You previously stated this was a 3 axis machine, so possibly you could use pins 8 and 9 but you will also have to rewire your breakout board etc.

07-01-2011, 04:58 PM
It seems strange, with the other PC no problems i am using the same software set-up same cables only difference is the buffer and the LPT output, what I was wondering is would the LPT card be using a different pinout, but I cant see why, I am going to borrow a USB to LPT and try that through the buffer see it it helps, fingers crossed, Im new to CNC so its all a learning curve

07-01-2011, 05:17 PM
USB to LPT to my knowledge has NOT worked for anybody to date.
Did you try it with the "buffer" and the old computer?
At this point, I am at a loss without sitting down with you and a meter to try and diagnose the system. That would be rather hard as it is a long swim to your place:})

07-01-2011, 05:22 PM
have you tried another computer with parallel port
it might just be that one of your pins is stuffed (sorry if that's too geeky!)

07-01-2011, 05:31 PM
Greatly appreciate your help and time on this problem

07-01-2011, 11:58 PM
have you buzzed the cable through and checked it is 1 - 1 on all 25 pins... a lot of odd problems of this nature that go from PC to PC are cable related...

08-01-2011, 09:56 AM
no I have not I will do that, as you say it`s i-1 so each pin goes straight through no crossovers?

08-01-2011, 10:28 AM
no I have not I will do that, as you say it`s i-1 so each pin goes straight through no crossovers?

Yes that's right, each pin should be connected to the same pin on the other end of the cable.

08-01-2011, 11:17 AM
The confusion comes from using a Parallel port but the cable used, should be a 25 Pin Serial cable.


08-01-2011, 03:33 PM
Check the pins on the cable, all appear to pin connected

24-02-2011, 04:33 AM
Ok update, it was the E-PCI card not putting out all the right signals , I went for a MOBO with built on LPT and it all working beautifully, it has taken me ages to get this machine running but the plus point is I have learned loads, so anyone out there having problems and coming to the end or your tether, hold on, with determination, money , sweat, swearing and confusion plus the knowledge you have some very clever chaps on this forum, you will come through and have people remark how good your work looks.......it`s worth it