I'm having intermittent issues with a new build machine 'loosing' the keyboard and looking for advice on what would cause this. The system is a Dell Optiplex 755 running Windows XP and a downloaded copy of Mach 3 downloaded about 2 weeks ago. I'm running a parallel port CNC4PC BOB driving a 4 axis milling machine (though only 3 axis are in use). The keyboard and mouse are generic Chinese USB units. The machine functions are consistently working properly - no signs of output conflicts, freezing, etc, and the mouse also consistently works fine. The PC is a new refurbished unit with a clean windows reload and is only running mach3 with no other software or interfaces.

The first symptoms were that the machine would not jog consistently by keyboard - it would start jogging but then stop after anywhere from 1-20 seconds and sometime restart if the key was held down. To me it was acting like a bad keyboard but swapping keyboards showed the same symptoms - it acted like an intermittent loss of signal. It would do this for both directions on all 3 axises. This seems to have gotten better over time (1-2 hrs of computer run time while working on other settings and wiring) but then it would loose the keyboard all together after 1-5 minutes of mach 3 run time - in this case the 'num/caps lock' lights would go out and no keys would work exactly as if it was unplugged. Unplugging the keyboard and plugging it back in to a different port would cause Windows to recognize it as a new device, install drivers and then it would work again, only to stop later. I tried swapping ports with the mouse and have used multiple USB ports to no avail.

The one consistency I have found is that the keyboard stops working immediately when the spindle is running - lights go out and no keys work. Unplugging and plugging back in while the spindle is on causes an error in Mach 3. (I do not recall what error exactly)

I have tried reloading mach 3 and have followed the direction with regard to rebooting after the parallel port driver install. It seems pretty clear to me there's some sort of a conflict between the Windows keyboard input system and Mach 3, but I'm not clear why or how. All of the Mach 3 functions seem to be working properly and there are no errors or notices from Windows or Mach 3 when the keyboard stops working. It's as if it just decides to ignore the keyboard, though since the mouse still works fine it seems like the USB ports are still working properly which points at the actual keyboard driver/interface somehow. 

I built a very similar machine using essentially the same PC roughly 3 months ago and didn't have this problem so I am quite confused. That machine was the same exact model of PC from the same supplier, but the 3 month difference could mean different software versions or something, and the video card I am using this time is different. The Mach 3 software was also recently downloaded vs the ~3 month old copy on the last machine. Not sure if any of this would make a difference, but putting it on the post in case it does.

Thanks,
     ~John

Well, after a fair bit of playing with things I've come to the conclusion that this appears to a noise issue, likely due to use of what I suspect is an unshielded parallel port cable. Not sure why noise on the parallel port would cause the USB keyboard to go wonky, but I was able to pretty conclusively pin it down to that cable, and upon consideration I realize that the cable I got is a generic computer parallel cable, vs the cnc4pc shielded cable I had on the previous setup. Hopefully replacing the cable fixes the problem.

I also have the same issue on our water jet but mine comes and goes I believe it's from interference/noise from the machine.  I'm not sure if my issue is that I have the computer in the same box as the servo drives and all of the machine wires and voltage transformer my thought was to separate the computer from the drive.  Any info that you have may help me to

Thanks
Tim

I have the same issue with jogging and I really think it's keyboard or keyboard driver related. It will jog fine then stop. I had an old ps2 keyboard trackball combo that was starting to get flakey. It craped out in the middle of a job so I grabbed one of the USB keyboards from another machine. I plugged it in and it works except it has the jog problem. It's an irritant more than a problem so I haven't tracked it down.
It's an adesso keyboaard so it's not junk.

This may help all of you.

http://www.machsupport.com/forum/index.php/topic,25616.msg180583.html#msg180583

Brett

Hi
I did some looking and we notice that when we up graded our chiller that we had a ground hooked up but it was not the way we had it before so we re-hooked the ground the same as we did with the old chiller that helped a lot we went to having the issue at least everyday to not having it for a week now.  I also found some noise filters at radio shack   ( http://www.radioshack.com/product/index.jsp?productId=2996360  )  and right now we unhooked the ground and only have these on the USB cables right by the computer so far so go but only been running for a hour now but normally it would have lost the keyboard by now for $3 we cant complain but no mater what I will hook the ground back up to the chiller better be safe that sorry.
I will report back to let you know how the filters worked after I get done testing for a few days