med ls -l /dev/ttyUSB* kom detta

pi@raspberrypi:~ $ su -
Password:
root@raspberrypi:~# ls -l /dev/ttyUSB*
crw-rw---- 1 root dialout 188, 0 Dec 1 12:10 /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 1 Dec 1 12:10 /dev/ttyUSB1
crw-rw---- 1 root dialout 188, 2 Dec 1 12:10 /dev/ttyUSB2
root@raspberrypi:~#