Check available serial line
Few of the computers have D shell 9 pin serial connector
You need probably a USB to serial adapter
If you have no D shell 9 pin port on your computer, connect your USB to serial adapter to one of the USB ports of your computer and install the necessary driver for it. Mostly Windows will do it in the background if you have internet connection.
Check the available serial ports using Device Manager and locate Ports (COM & LPT). The name of the serial port is COMn, where n is an integer number. Use this port number in the instance of SerialIface.
Connect your USB to serial adapter to one of the USB ports of your computer Use dmesg command to find the USB port assigned to the adapter.
dmesg | grep USB
You should see /dev/ttyUSBn in the output of the command above. n is an integer value mostly 0.