Garmin Mobile PC with Trimble Placer 450 GPS?

Greetings everyone,
I have been trying to get Garmin Mobile PC to work with a vehicle mounted Trimble Placer 450 GPS. The Trimble GPS starts out in their proprietary TAIP protocol, which I have switched over to NMEA for output on the MDT (mobile data terminal) port on the Placer unit.

My problem is this. The Trimble unit is sending out NMEA sentences, but the Garmin software isn't reading them. I've verified that the sentences are coming out via a Terminal program. I've also gotten the Placer 450 to work with iNav iGuidance, Street Atlas 2K9, Streets and Trips, Etc... The Garmin program seems to be the only one that doesn't work. In looking at the output from the Placer 450, I've noticed that some of the data spaces are blank. So for example you might see:

$GPGGA,000105.995,0000.0000,N,00000.0000,E,,00,50.0,,M,0.0,M,,0000*77

If I use GPSGate to simulate a GPS I've noticed there is always a '0' in those blank fields. So I'm thinking the ,, is confusing the Garmin software. I've also tried using GPSGate to convert the TAIP messages to NMEA, but that doesn't seem to work either. MPC sees that there's a GPS there, but no tracking information ever comes up on the GPS info screen. Anyone have any ideas?

Try to set the Trimble unit to NMEA, and then use GPS Gate + Garmin Mobile PC .

Welcome to the forums, ND4SPD.

I think this is a problem with GMPC not playing nicely with real COM ports any more. As Marvin suggests, filtering it with GPS Gate should provide a COM port that Garmin will respond to.

Terry

Tried doing the GPS Gate filtering... but it doesn't seem to affect the null spaces I mentioned.

Here is the Raw TAIP output:

>RPV84812+4305930-0894957200006701<
>RPV84812+4305930-0894957200006701<
>RPV84812+4305930-0894957200006701<
>RPV84812+4305930-0894957200006701<

Raw NMEA directly from the 450

$GPZDA,233816.000,27,01,2009,,*54
$GPGGA,233317.000,4303.558102,N,08929.743180,W,1,03,02.91,+000320.03,M,,M,,*7B
$GPGLL,4303.558102,N,08929.743180,W,233317.000,A*2D
$GPGSA,A,2,21,18,22,,,,,,,,,,0003.08,0002.91,0001.00*39
$GPVTG,066.611,T,,M,000.1271,N,000.2356,K*61
$GPZDA,233817.000,27,01,2009,,*55
$GPGGA,233317.000,4303.558102,N,08929.743180,W,1,03,02.91,+000320.03,M,,M,,*7B
$GPGLL,4303.558102,N,08929.743180,W,233317.000,A*2D
$GPGSA,A,2,21,18,22,,,,,,,,,,0003.08,0002.91,0001.00*39
$GPVTG,066.611,T,,M,000.1271,N,000.2356,K*61
$GPRMC,233317.00,A,4303.558102,N,08929.743180,W,000.127,066.61,270109,,*14

Through GPS Gate

$GPZDA,234029.000,27,01,2009,,*57
$GPGGA,233317.000,4303.558102,N,08929.743180,W,1,03,02.91,+000320.03,M,,M,,*7B
$GPGLL,4303.558102,N,08929.743180,W,233317.000,A*2D
$GPGSA,A,2,21,18,22,,,,,,,,,,0003.08,0002.91,0001.00*39
$GPVTG,066.611,T,,M,000.1271,N,000.2356,K*61
$GPRMC,233317.00,A,4303.558102,N,08929.743180,W,000.127,066.61,270109,,*14
$GPZDA,234030.000,27,01,2009,,*5F
$GPGGA,233317.000,4303.558102,N,08929.743180,W,1,03,02.91,+000320.03,M,,M,,*7B
$GPGLL,4303.558102,N,08929.743180,W,233317.000,A*2D
$GPGSA,A,2,21,18,22,,,,,,,,,,0003.08,0002.91,0001.00*39
$GPVTG,066.611,T,,M,000.1271,N,000.2356,K*61

And here is a dump from my Belkin Bluetooth GPS which works with Mobile PC

$GPGGA,234606.096,0000.0000,N,00000.0000,E,0,00,50.0,0.0,M,0.0,M,0.0,0000*7C
$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05
$GPGSV,3,1,12,21,89,000,27,14,70,000,00,22,63,000,00,18,42,000,00*77
$GPGSV,3,2,12,03,40,000,00,09,23,000,00,10,08,000,00,29,02,000,*74
$GPGSV,3,3,12,28,-05,000,00,26,-06,000,,01,-06,000,,06,-07,000,*71
$GPRMC,234606.096,V,0000.0000,N,00000.0000,E,,,120928,,*1E
$GPVTG,,T,,M,,N,,K*4E
$GPMSS,0,0,0.000000,200,*5A
$GPGGA,234607.096,0000.0000,N,00000.0000,E,0,00,50.0,0.0,M,0.0,M,0.0,0000*7D
$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05
$GPRMC,234607.096,V,0000.0000,N,00000.0000,E,,,120928,,*1F
$GPVTG,,T,,M,,N,,K*4E

Totally meaningless to me. I was going to suggest the data rate might be too high (GMPC tops out at 38,400) but you said it works with S&T (4800).

Terry

I can try bumping the data rate down to 4800 BPS, it's at 9600 right now. I've done a GPS simulation using GPS Gate and it will pick up the simulated data coming across the emulated port so I don't think it's the baud rate. Probably sloppy programming on Garmin's part.

Looks like I've found the culprit... the Garmin software apparently doesn't like the fact that the Placer 450 doesn't output the $GPGSV (Satellites in view) command. Using GPSGate I created my own NMEA log file and added in the $GPGSV sentences from my BT GPS and voilla it worked. Now, all I have to do is convince Garmin to issue a patch addressing this issue.

Check the manual for the GPS receiver. Perhaps there is a way to enable GSV.

It is as likely for Trimble to offer a firmware update as Garmin to patch GMPC for that GPS only.

Terry