List your all USB peripheries
lsusb
Connect your USB serial cable and list all USB peripheries once again. Note the new device (like 0557 an 2008)
mobprobe usbserial vendor=0x0557 product=0x2008
dmesg | grep ‘ttyUSB’
note: ttyUSB0
chmod 777 /dev/ttyUSB0
To connect with serial port use
cu -l /dev/ttyUSB0 -s 9600
you are now connected with serial port, type ~. to quit.