Machine acting weird

Hi all,

I need your help. I have a PC running with LinuxCNC. I have 2 parallel ports for 2 different machines. I had everything working a few weeks ago.

Now on one of my machines I have a weird problem. The mill is not working anymore. If I try to jog any X, Y or Z non of the axis is physically moving. I see that in AXIS the machine is moving and the coordinates change, but no physical movement. If I home the machine the Z axis is homing first, but only in the software, no physical movement. If I let the machine running in the homeing cycle at some point it stops with the Z axis and continues with the X axis. The X axis is then moving in the software as well as physically. Once X reaches its limit switch sensor it doesn't back of as usually and continues to run even behind the X axis limit switch.

I have for sure not changed anything on the wiring. I tested that all limit switches are coming back to linuxcnc and it's all working. So the inputs are fine. I haven't tested the output voltage to the drivers yet. But the fact that the machine during the homeing cycle works on 1 axis makes me believe that the wiring should be fine.

How can I find the issue with the machine?

The other mill on the other paralel port works just fine.

Really sounds like an electrical issue with the step/dir outputs to me,
especially the inability to change the X axis step drive direction.

I think so too, but why is the x axis moving during the homing cycle and not when I jog it?

May have to do with the states of other output pins
(a missing ground/common can cause this kind of behaviour)

I would measure the direction signals at the drives when you jog
in either direction, to see if they have valid levels.

Mystery solved. I had the enabled of all drivers bridged (connected or whatever the right term is) but the connection was interrupted. Technically the X axis should not have been able to move, because the interruption was before. Well, it works. So I am happy.

I had the enabled of all drivers bridged but the connection was interrupted. Technically the X axis should not have been able to move, because the interruption was before. MLM019T5LP9