Unable to assign the USB from computer 2 to computer 1

KVM Model:

HDMI 2.1 KVM w/EDID & Serial Control - Single Monitor - Four Computer

USB Interface (5-gigabit or 10-gigbit):

10-gigabit


Problem:

I cannot switch the USB assignment from computer 2 to computer 1 via the serial console.

I’m using the serial console to send commands to switch computers/USB/audio with buttons on an Elgato Stream Deck. For some reason, I am unable to switch the USB from computer 2 to computer 1.

The command is accepted, but the devices do not switch.

Sample Commands:

stty -F /dev/ttyUSB0 19200
echo -e "U = 2\r\n" > /dev/ttyUSB0
echo -e "U = 1\r\n" > /dev/ttyUSB0

Output of cat -v < /dev/ttyUSB0:

U = 2^M^M
>
U = 1^M^M
>

Other Notes:

  • I can switch the USB to computer 1 from computers 3 and 4. I’m switching from computer 2 to computer 4 and then to computer 1 as a work around for now because I currently only have three computers connected.
  • When the USB is set to follow it changes from computer 2 to computer 1 as expected.

Two unrelated questions:

  1. Does setting the audio source not work when the audio is extracted from HDMI? Setting the audio source via the serial console does not seem to do anything. I’ve ordered some 3.5mm cables in case that’s the situation, but it seems like it should be possible to use the extracted audio.
  2. There are hotkeys to change the following setting separately for the front and rear USB ports. Are there serial console commands to assign each to a separate computer?

maybe try holding the buttons to reset the kvm.

theres also a keyboard shortcut to “not” switch usb3 ports and that may have been toggled on accidentally. (which might be a different state than otherwise). The press and hold the two buttons to reset should reset all the internal state

I’m you’re replying wendell beause I have no clue about serial commands xD

No luck with either the reset or the factory reset, unfortunately. I still can’t change the USB assignment directly from computer 2 to computer 1.

maybe try adding a space at the end? does it work when changing with the button?

A space made no difference, unfortunately.

Is there a hotkey for switching just the USB port to a specific port? I only saw the options to toggle following.

I have discovered something though: if I unplug my camera (a Logitech BRIO), whatever device I have plugged in on the other port (regardless of front or rear port) will switch from computer 2 to computer 1 directly.

I’m not sure why that would make a difference, especially since it works fine with the camera connected when switching from 1 → {2, 3, 4}, {3, 4} → 1, and 2 → {3, 4}.

Given this: here is some potentially relevant information:

Computer 1: Linux
Computer 2: Windows 11 (work machine, always on the latest updates)
Computer 3: Windows 10 (work machine, very locked down and secured)

My initial thought there was that Windows 11 was somehow preventing the devices switching when the camera was detected, but when moving to ports {1, 3, 4} everything works as expected between all computers.

the hid ports are all grouped together whereas usb3 is more like a mechanical switch when switching inputs. thinking about it for a sec I’m not sure what the internal state would have to be for the apparent external state to map to this config unless the USB stack has crashed so how

unplugged from from Power and USB for 5 mins to clear internal state?

No changes after unplugging for 5+ minutes.