NMEA, Baud and other stories

[TiggerToo]

Trying to get a Garmin 450 to communicate with a Navman 7200.

Garmin manual says

"The output from the GPS to VHF is set on Chanel 2 is at 0183 NMEA and I have checked the signal at the VHF end and there is a signal. Now the only thing to do now is get the format hhddmm or hhddmm.mm set for the radio to read the information . I did not have this info at hand but have it now and have forwarded it to Andy . it may require changing the output format from the GPS but it is a matter of reconfiguring it . "

Navman 7200 says
No position information is displayed.
The GPS cable may faulty or the GPS setting may be incorrect.
a) Check that the GPS cable is physically connected.
b) Check the polarity of the GPS cable.
c) Check the baud rate setting of the GPS if applicable. The baud rate setting should be 4800
for NMEA or 38400 for NAVBUS. Parity should be set to NONE.

what should I do? Where should I set up the confirgurations?

 

[pappaecho]

NMEA is a sort of current loop, a variant of a serial interface. Forget parity settings for a start.
Really the two important parameters are baud rate, and 4800 is standard. The other important parameter is to connect the transmit from one device to the receive of the other and vice versa. I would follow the instructions and see what happens, you certainly wont blow anything up. NMEA 183 has from memory so variants as to whether one device transmits and the other receives, or both fully interact. For example a GPS transmits the latitude and longitude to the dsc radio, which does not need to send anything back, whilst a autohelm my need to send data back. If for example the system is in full duplex mode, the fact that as DSC radio wont send anything back wont matter to the host

 

[rob2]

Don't know the Garmin 450 as such, but most Garmins default to their own language , so the output needs to be set to the NMEA option. It'll be somewhere in the menu system, try looking for settings, output, etc.

Rob.

 

[SJF]

First you should double check that the wiring connections are correct.

Wiring Connections Garmin GPSMAP 450 to Navman 7200:
Garmin GPSMAP 450 	    Navman 7200
Grey (Port 2 tx)  ------    Yellow (NMEA IN +)
Black (Ground)	  ------    Green (NMEA IN -)

You then need to check the following settings on each device:
On the Garmin you need to ensure that Port 2 is set to output NMEA data at 4800 baud. As I have a 450s I can tell you the steps are:

• Turn on unit
• From the home page select configure
• Select Communications
• Serial Port 2 (defaults to no output on mine) select NMEA Standard

(You should be able to leave all the NMEA 0183 Setup unchanged from its defaults for this to work)

On the Navman you need to ensure that NMEA is set as the GPS Source (Page 22 of the manual section 3.7.1) I don't have a navman so am unable to confirm the exact keystrokes for this unit.

Information Sources:
Garmin GPSMAP 450 Wiring Diagram
Navman 7200 VHF Wiring Diagram
Navman 7200 VHF Operators Manual

Hope this is of some use.
Simon