SKR Pro Serial Connection Issues

Hi there,

I already have a couple of hours on my LR4 with SKR Pro, enjoying it a lot!

Today, I was preparing the next cut, and jogging the CNC to the origin from my PC with Repetier (really nothing special). Suddenly it stopped, Repetier gave me an error message and ever since I keep hearing the Windows “dudun” sound of a device connect and disconnecting every 1-2s, as if someone keeps plugging it in and out continuosly.

Here’s the things I tried:
-tested 5 different cables (including the cable which was part of the set), exactly the same issue
-tested 3 different PCs (2x Win11, 1x Win10), exactly the same issue
-tried whether I can reproduce/force/inhibit the behaviour with jiggling/holding the cable at certain angles near the plugs, also close to the board - no success at all.

What I did notice is that the red LED close to the USB port keeps being illuminated, even if it is diconnected from the PC at this moment - the LED also lights up when there is no 24V power on the board. I am not sure how this LED is wired, but I suspect this means the board gets the 5V through the USB, but either the data connection is wonky or the chip is defective…

is there anything else I should check?

Thank you!

cc @vicious1

Unplug the PC and use the LCD to jog the machine.

Using a connected PC can cause a few issues and is typically only used for some laser work. The most common issue is the Pc and control board on different circuits and causing stray current or something.

I recommend only using the USB cable on an MPCNC with a fixed control board and for lightburn tests only. Any other time load your Gcode on the SD card and run from there.