Configuring FLDIGI to work with SCU-17 on Ubuntu 13.10, I ran into a permissions issue.
Normal users can't access /dev/ttyUSBx
You have to:
sudo chmod o+rwx /dev/ttyUSB0
sudo chmod o+rwx /dev/ttyUSB0
Or (to make permanent) - from some sites on the internet (links lost - sorry):
sudo adduser youruser
dialout
sudo reboot
