Picks wrong printer

smwoodcrafts

Hi, Im running Repetier-Server pro on a Raspberry Pi. I have 2 printers hooked up and they both run fine. A Crealty Ender 3V2 and an Elegoo Neptune 3 Plus. I don't always use both printers so if I turn on just the Neptune, Repetier says I turned on the Ender. If I unplug the Ender, it will switch to the Neptune but why would it be doing that? They are on 2 separate usb ports.

Lout

The devices /dev/ttyUSB0 etc are dynamic and can swap between the different USB ports depending on when they start up.

Use the /dev/serial/by-path/platform......... devices.  These will always point to the correct USB port.

Use dmesg to watch for when the USB port is plugged in and what port was configured

eg:

[   11.508708] ch341 1-1.2:1.0: ch341-uart converter detected
[   11.560645] usb 1-1.2: ch341-uart converter now attached to ttyUSB0

The translates to /dev/serial/by-path/platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.2:1.0-port0 on my PI.  Yes these are symbolic links to the ttyUSB device, but the system maintains the links to ensure that the device points to the correct device.

smwoodcrafts

Yikes!  I'm afraid I'm missing something here. Can you explain how I do this?

Repetier

Port names in /dev depend on activation order and you likely have selected /dev/ttyUSB0 or similar in that folder. So depending on order you activate printers it is randomly correct or not. 

Use insted in connection settings a port name that starts with /dev/serial/by-path/... and the usb port you connect it to is used to determine which printer gets connected and no random association any more.