dmesg --follow
then plug in the scanner:
[ 1703.081249] usb 1-4: new high-speed USB device number 6 using ehci-pci
[ 1703.240272] usb 1-4: New USB device found, idVendor=04b8, idProduct=012f, bcdDevice= 1.00
[ 1703.240275] usb 1-4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1703.240277] usb 1-4: Product: EPSON Scanner
[ 1703.240279] usb 1-4: Manufacturer: EPSON
and put the IDs into the proper udev rule /lib/udev/rules.d/99-xsane.rules
:
# Epson Perfection V350 Photo
SUBSYSTEM=="usb", ATTRS{idVendor}=="04b8", ATTRS{idProduct}=="012f", MODE="0666", GROUP="scanner"
sudo udevadm control --reload-rules && sudo udevadm trigger