# Configuring File TNC Ports

Terminal-Node Controllers (TNC) may be connected through a computer using other interfaces than serial ports or network-connected software daemons. For those that use non-standard file names, this port driver supports opening such files to access the TNC (or kernel equivalent) as a KISS device.

To add a new TNC port of this type, click the Add button on the Configure Ports tab. The port editing dialog will appear. Set the port type to File_TNC.

The other parameters you will need to specify for the TNC are:

- the name of the file to which the TNC is connected.
- The callsign you will be using to identify your transmissions over this port. This should be your legal government-assigned callsign with an optional numeric SSID suffix from 1 to 15.
- Whether or not you want to allow YAAC to make transmissions through the port. If left disabled, you will only be able to monitor APRS traffic through this port. You must specify a callsign to be able to transmit.
- The sub-list of aliases that will be digipeated through this port, based on the total list of known aliases defined in the general configuration. If YAAC receives a message with one of the checked digipeat aliases and this port is enabled for transmission, the message will be re-broadcast through the radio on this port. If no aliases are selected, this port will not digipeat. Multiple aliases can be selected. The aliases must also be enabled for digipeating on the configuration dialog's Digipeat tab.
- The protocols that can be transmitted through this TNC. Generally, only one protocol should be used on a given RF channel to avoid confusion of other stations and wasting of bandwidth. Which supported protocols should be transmitted out a TNC port is specified by checking the corresponding checkboxes. Note that YAAC will support receiving all protocols through one TNC port, recognizing which protocol is in each AX.25 frame by the PID field; this merely restricts which protocols YAAC will send on a port.

The "Test Port" button provides a means of verifying that you have connected to the correct place; it opens a terminal window connected to the configured file so that you can manually test the TNC for the desired operation. To complete testing, close the terminal window.

Once you have the settings the way you want them, click OK. Ensure that the TNC is connected to the port before you click OK.