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My pattern router that has been rock solid position wise forever started loosing position. At the same time I had a few times when launching UCCNC it would fail to see the UC-100. I put a new USB cable on it and it's working great but as we all know that doesn't mean a thing in this game.

So my question is: Can a bad USB cable on a UC-100 cause position loss during a run but not throw a lost communications error. Because the only thing I did was shut down UCCNC, replace the cable and restart UCCNC. Even used the same USB port on the computer.

The first loss was measured at .047" on the Z axis. The second was .372" on the Y and the third was a whopping 3" or more. I eyeballed that one so it was give or take a bit:)

Thanks

If the UCCNC does not see the UC100 then the device is not available in Windows. It is unconnected or the USB drivers are not yet installed.
A non contacting cable means no connection between the computer and the UC100 and ofcourse then the communication will break and the device will disconnect.

Yes but can it cause this:

Can a bad USB cable on a UC-100 cause position loss during a run but not throw a lost communications error.

Edit: Can an intermittently bad USB cable on a UC-100 cause position loss during a run but not throw a lost communications error.

No, it can't, because if there is data packet error the communication protocol corrects it with re-requesting and resending or if that does not work then it cuts the connection.

Well as it always happens I change something that shouldn't fix a problem that seems to fix the problem.

I ran the machine all day today after changing only the USB cable and it held position the whole time.

I had unexplained periodical problems with my UC100 when first used. I replaced the USB cable it was shipped with with a quality shielded cable and it's been rock solid since.

Dan

The funny thing is it's the original cable from a UC-100 that I bought before there was a UCCNC and it's been fine for all those years so I'm going to assume that either it's not the problem or something internally in the cable broke down.

Time will tell.

High speed USB (2.0) has a 480Mbits/sec transfer speed, so the frequency is really high and so even if the cable is partly broken and cannot be visually seen can cause issues.
It's also possible that not the cable is the issue, but something started generating more noise in the control system than before. E.g. capacitors drying out in a power supply.

And if noise is the problem then the best is to find out what causing it, or a shorter USB cable can also help in some cases,
because how the noise effecting USB devices is that the ground of the PC is getting the noise.
The ground potential point moves. USB is ground referenced, so the ground of the UC100 is the same potential as the PC ground.
So, then the ground potential of the UC100 will also move when the PC ground potential moves.
There is an issue if the noise amplitude is high enough and it's changing rate is also high, because the cable has an impedance which will limit the possible rate of voltage potential change.
There is a frequency rate point where above the cable will not be able to follow, the 2 potentials will shift and the PC ground and the UC100 ground will be no more the same potential which will cause communication errors and finally communication losses if there are enough errors for that.

A shorter and thicker cable always has less impedance and so the higher the noise dV/dt can be before the issue occurs is how a shorter cable may resolve this issue, but ofcourse it depends on the properties of the noise...

I have spares of everything including the computer, UC-100 and the drives. One way or another I'll get it figured out the same way I always do. Keep changing stuff until the problem goes away. This is my main money maker and I can't have it chewing up patterns.

Any replacement cable brand/model recommendations?

Which plug is on the UC-100? I always get the small ones confused.