Garmin GPSMAP 178 Owner's Manual page 97

Port 2:
• Garmin DGPS – used to connect the GPSMAP 178/178C with a Garmin DGPS beacon receiver.
• Other DGPS – allows DGPS input using a standard RTCM format, without any output capabili-
ties.
• NMEA In/NMEA Out – supports the input/output of standard NMEA 0183 data and DSC. You
may also adjust the NMEA output.
• RTCM In/NMEA Out – allows Differential GPS (DGPS) input using a standard RTCM format and
also provides NMEA 0183 output.
• None – provides no interfacing capabilities.
To select an input/output format:
1. Select the desired Port tab, then highlight the 'Serial Data Format' field and press ENTER.
2. Use the ARROW KEYPAD elect the desired setting and press ENTER.
To select a transfer mode:
1. Use the ARROW KEYPAD to select 'Garmin Data Transfer' in the 'Serial Data Format' field.
2. Highlight the 'Transfer Mode' field and press ENTER.
3. Use the ARROW KEYPAD to select the desired setting and press ENTER.
You may also adjust the NMEA output to enable/disable certain sentences and adjust the number of
Lat/Lon output precision digits. You must have one of the ports set to NMEA In/NMEA Out to use this
option. Settings affects both Port 1 and Port 2 NMEA outputs.
Reference
Main Menu: Comm Tab
When transferring data between two Garmin units,
be sure to always set one to 'Host' and use the other
unit to either Send or Request the desired data.