Loopback Device

A loopback is a device that sends the signal back through the same port as it is sent out of. It is used for testing purposes and is not used under normal operations.

To make a loopback device, you will need a 9-pin or 25-pin connector and three pieces of wire.

Loopback Device For a 9 Pin Connector

Loopback Device For a 25 Pin Connector