Add Garmin 64st to your list of supported GPS Units
To use the Garmin 64 as a live tracking device, please configure the Garmin 64 to be in "Spanner" mode:
This will allow you to choose two modes of operation when the GPS is connected to the PC. "Mass Storage" mode is for transferring markers, routes, tracks, and maps. The other general connection mode is for live tracking. Use this mode, along with the Garmin GPSMap 62s USB setting in Terrain Navigator Pro to display your position in real-time in TNP.
Jon Nowlin commented
No matter what selection of options on the Garmin 64s setup, I cannot get real-time positioning to work with TNP. Very frustrating!
Note: While not officially supported, we have determined that the use of the GPS Setup setting in Terrain Navigator Pro for the Garmin GPSMap 62s is fully compatible with the GPSMap 64. In Terrain Navigator Pro, open the GPS menu, choose Setup (not GPS Setup Wizard) and select the Garmin GPSMap 62s USB as the unit to connect TNP with the Garmin 64 GPS.