Problem Solved: Map 276C AP NMEA Interface
 

Today, I am pleased to announce that, the problem I had reported
here with the software of my GpsMap 276C was solved by Garmin, with the
release of the 3.21 Beta Software Update. Thanks Garmin!

This Update included the BWC, XTE and VTG messages in the batch of NMEA
messages always sent, exactly as I had asked to Garmin when I have
reported the problem almost 4 month ago, as showed by the output of
Windows Hyperterminal .

For those interested in the details, follows a sample of the NMEA
messages now being sent by GpsMap 276C after the 2.31 beta software
update:

$GPGLL,1248.7047,S,03827.5797,W,010001,A,A*41
$GPBOD,345.6,T,8.6,M,BA01,AIC*04
$GPBWC,010001,1248.4128,S,03827.6978,W,338.4,T,1.5 ,M,0.314,N,BA01,A*63
$GPVTG,94.9,T,117.9,M,0.0,N,0.0,K,A*19
$GPXTE,A,A,0.04,L,N,A*07
$PGRME,6.7,M,9.5,M,11.6,M*15
$PGRMZ,2,f,3*19
$PGRMM,WGS 84*06
$GPWPL,1247.5788,S,03830.6300,W,CA05*4C
$GPRMC,010003,A,1248.7047,S,03827.5797,W,0.0,94.9, 290505,23.0,W,A*03
$GPRMB,A,0.04,L,AIC,BA01,1248.4128,S,03827.6978,W, 0.314,338.4,,V,A*33
$GPGGA,010003,1248.7047,S,03827.5797,W,1,11,0.8,1. 0,M,-10.5,M,,*66
$GPGSA,A,3,01,03,06,,14,15,16,18,19,21,22,25,1.5,0 .8,1.3*3B
$GPGSV,3,1,12,01,43,333,54,03,43,237,49,06,05,030, 43,09,02,120,00*7C
$GPGSV,3,2,12,14,86,032,47,15,46,140,45,16,18,315, 47,18,19,143,49*70
$GPGSV,3,3,12,19,21,221,35,21,29,091,49,22,39,174, 43,25,17,000,50*70


After updating my Map276C to the 3.21, I have made a simple test with
my AH/ST 4000, and the bearing to waypoint (BRG) showed by my Autohelm
Autopilot AH/ST 4000 is now practically equal to the BRG showed by the
Map276C. The BRG angle difference is only a mere 1 degree caused, I
think, by the fact that my AP is rounding the bearing angle value to a
integer using a different procedure of the rounding made by the
Map276C. For example, the AP rounds 1.4 degrees to 1, (which I think
is the correct way), whereas the gps rounds it to 2.

Anyway, the error is practically insignificant, and reflects only the
values showed in the displays, and I am satisfied with the solution.
Incidentally, the fix was released on May, 24 which is my birthday,
so....

Thanks again Garmin ...

Pascal Goncalves