Plug one side of your VGA-to-serial cable adapter into your video source. VGA cables have a rectangular-shaped, blue plug on each end. The VGA side on the adapter is rectangular in shape and has 15 tiny pins on the inside. For example, if you are working with a computer monitor, plug the cable adapter into the appropriate port in the monitor (the exact location depends on model type).
Plug a serial cable into the serial input on the cable adapter. The end of a serial cable is rectangular in shape and has nine holes inside the plug. The serial input on the adapter is shaped identically to the cable and has nine pins instead of nine holes.
Connect your serial cable to the serial port on your computer. The serial port on a computer is typically located on the rear of the case. The port looks identical to the plug on the end of the serial cable and has the same nine-pin configuration. Computer signals are transmitted from the connected device to the serial cable and into the connected device via the serial adapter.