A. Use the following table as a general guide when setting up your GPS unit to interface with another device. The interface setting can be found under the main or auxillary menu on your GPS and then under interface or I/O setup.

Device Type	Interface Setting	Transfer Mode or Baud
Autohelm/Radar	None/NMEA	4800
Manual-Tune Differential/GBR21	RTCM/NMEA	4800, Beacon Freq, BPS
Auto-Tune Differential	RTCM/None	4800
Plotter/Yeoman Chartplotter -or- other Chartplotter with waypoint transfer	NMEA/NMEA	4800
Computer - Real-Time Plotting	None/NMEA	4800
Computer - Transfer Waypoints *Note: Some programs allow real time plotting in this mode	Grmn/Grmn Garmin Data Transfer Garmin Data Transfer	Host or Slave mode
GARMIN Unit to GARMIN Unit	Grmn/Grmn Garmin Data Transfer Garmin Data Transfer	GPS #1 - Host or Slave mode GPS #2 - Send or receive data ex: "SEND WPT" or "Request RTE"

Notes:

1. Garmin GPS's can output to a maximum of 3 devices simultaneously.
   
2. Garmin GPS's can listen to only 1 device at a time.
   
3. Garmin GBR21 can output to a maximum of 3 devices simultaneously.
   
4. Garmin GBR21 can listen to only 1 device at a time.
   
   
   
   1. Set as follows when interfacing multiple GPS's with a GBR21:
      
      
      
      1. GPS #1 RTCM/NMEA (tunes GBR21)
         
      2. GPS #2 RTCM/None
         
      3. GPS #3 RTCM/None