Garmin GPS 12CX - Manual (Page 50)

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Transfer Mode Field
I/O Format Field
Interface Setup Submenu
P a g e
R E F E R E N C E
Main Menu—
Interface Setup
Submenu
Interface Setup
The GPS 12CX’s interface page lets you specify the
formats for connecting external devices. There are six
options: GRMN/GRMN, None/None, RTCM/None,
RTCM/NMEA, NMEA/NMEA, and None/NMEA. Each
option lists the input format first, followed by the output
format.
To select an I/O format:
1. Highlight the I/O field and press ENTER .
2. Select the desired setting and press ENTER .
The GRMN/GRMN setting is a proprietary format
that lets you exchange information such as waypoints,
routes, and track logs between two GARMIN GPS units
or the GPS 12CX and a PC. The transfer mode field is
directly below ‘GRMN/GRMN’, and allows you to specify
what information to request or send to a second GPS
unit. The ‘Host’ setting lets you control all data transfer
functions from the second GPS unit or a PC.
To select a transfer mode:
1. Highlight the transfer mode field and press ENTER .
2. Select a desired setting, and press ENTER .
To disable all interfacing capabilities, select the ‘None/
None’ setting. If you want to output NMEA data without
any differential input capability, select ‘None/NMEA’.
Interface Setup: DGPS
The last two format settings allow the differential-
ready GPS 12CX to accept RTCM DGPS corrections in
RTCM 104 version 2.0 format. Using DGPS corrections
will improve receiver accuracy to 1-5 meters, regardless
of errors induced by the U.S. Dept. of Defense Selective
Availability (SA) program. Two RTCM options are avail-
able: ‘RTCM/NONE’, which allows connection to a bea-
con receiver with no output capability; and ‘RTCM/
NMEA’, which allows DGPS input and NMEA output.
When ‘RTCM/NMEA’ is selected, the GPS 12CX will
either automatically try to tune the last frequency and bit
rate you selected or will switch to the default frequency of
304.0 kHz with a bit rate of 100 bps if no previous beacon
has been tuned. (You may also enter your own frequency
and bit rate if desired.) This information is used to tune/
control an optional GARMIN GBR 21 differential beacon
receiver.
Note: Use the ‘RTCM/NONE’ setting if your beacon
receiver does not support these software-driven controls.