Comment # 2 on bug 1233416 from Johannes Meixner

Alex Ustinov,

instead of running all CUPS backend in
/usr/lib/cups/backend/ via "lpinfo -v", you could
run each of them one after the other manually.
When you run a CUPS backend manually without
command line options, it autodetects and reports
the devices on stdout (plus debug messages on stderr)
which belong to the particular CUPS backend,
e.g. (preferably run CUPS backends as 'root')
# /usr/lib/cups/backend/usb
autodetects and reports USB printers.