In order to get USB to serial converters working in linux with minicom, you must chmod give non-root users the ability to access the USB to serial device.
Install minicom using the normal methods for your distro. Then start minicom as root.
su –
minicom -s
set to 9600 8N1
save settings and default and exit minicom.
Next give normal users the ability to use the USB serial port.
chmod a+rw /dev/ttyUSB0
exit to a normal user shell and try to start minicom