### Testing a Port with a Loopback Plug

Use this procedure to troubleshoot a Digi serial port.

1. Connect a loopback plug to the port.

   Note: Alternatively, you can tie the transmit (TxD) and receive (RxD) signals together on the port or on the end of an attached cable.

2. Test the connection by entering the following at the UNIX command prompt:

> `# cat < /path/device &
> # date > /path/device`

> where `path` and `device` are the path and device name for the port respectively.

> The `date` command is used for this simple test to provide text output (there is no other significance).