I have never experienced a bug like this with Mach 3 either through the parallel port or UC100 motion controller.  Nor have I ever seen one reported on here.  I think therefore it must either be in the motion controller or possibly a wiring problem between that and the drives.  Poor or intermittent contacts, and / or earthing issues, can give rise to odd phenomena.

> in the motion controller or possibly a wiring problem between that and the drives

In this case these wires or controller should alter the mach3's memory content directly. Otherwise the machine can behave in any way, but the numbers in the mach3's log should be correct.

Well there is a fairly intimate 2-way connection between the motion controller and Mach 3.  This must be so as for example when probing the MC has to tell Mach when and where it has stopped.  So I suspect that there is a bug in the MC software

Are you using a licence file that was supplied with the breakout board?

This must be so as for example when probing the MC has to tell Mach when and where it has stopped.

There is no need to get access to all mach3 memory to do so. If it is, it is a major design flaw in mach3 itself regardless how often it leads to bugs. And even if it is, in the log we see that mach3 got perfectly correct touch coordinates and only then decides to go wrong way. So it must be very strange bug if it is a driver/controller/wiring bug.

Are you using a licence file that was supplied with the breakout board?

I am using mach3 as it came with completely new machine, it says it is licensed to machine manufacturer. I do not know if it is genuine license or not.

Well that seems to exhaust all the possibilities then.  Can't help any further.

I actially posted it as a fun story, i did not hoped anyone will help me with this, considering mach3 developers abandoned it 15 years ago. Thanks for trying!

Well that was a waste of cycles all round then.

Thanks everyone for the assistance. I have it sorted out. Turns out that the motion controller had issues. I now have a new one installed.

Cheers