Select Setup > System > Interface.

Garmin Spanner

Allows you to use the device USB port with most NMEA 0183-compliant mapping programs by creating a virtual serial port.

Garmin Serial

Sets the device to use a Garmin^® proprietary format to exchange waypoint, route, and track data with a computer.

NMEA In/Out

Sets the device to use standard NMEA 0183 output and input.

Text Out

Provides simple ASCII text output of location and velocity information.

RTCM

Allows the device to accept Differential Global Positioning System (DGPS) information from a device supplying Radio Technical Commission for Maritime Services (RTCM) data in an SC-104 format.

MTP

Sets the device to use Media Transfer Protocol (MTP) to access the file system on the device instead of mass storage mode.