NMEA - Talkers and Listeners

mcaswell · May 24, 2010

You can look at the wiring diagrams in the manuals... some may have NMEA IN (listener), or OUT (talker), or maybe both (like the GPS). Multiple listeners can connect to one talker, but if you have multiple talkers that need to feed into one listener, you'll need a multiplexer.

Also, keep in mind, some of the devices may have proprietary interfaces instead of standard NMEA. For instance, the tri-data almost certainly just has seatalk... if you want it to be able to talk/listed to other devices, you'll need a seatalk-NMEA converter. Not sure about the simrad AP.

Anyway, rather than looking specifically at whether each device is a talker and/or listener, it might be better to think of it in terms of what information is being sent from each, and and whether or not you need that information to be available to the other devices.

For instance, you certainly would want AIS to be sent to the chartplotter, and for GPS to be sent from the chartplotter to the VHF. But do you need the tri-data to be able to talk to the other devices? Probably not. You might want the depth to display on your chartplotter, but other than that, you could skip the seatalk converter box.

Anyway, with the list of equipment you have, I don't think you'd need a multiplexer. The only possible "crash" situation of multiple talkers to one listener that I can see would be if you wanted the tri-data and AIS to both send data the chartplotter, and again, you probably don't need that. However, my Garmin GPS (545) has two "channels" of in/out (so, in other words, I could connect two separate talkers to the GPS without any additional equipment needed)... yours may too. In that case, if you did want the tri-data to send data to the GPS, you still wouldn't need a multiplexer.

--Michael

chuckwayne · May 24, 2010

HI Jim,
you've got 2 talkers there, the AIS and the GPS. The st60 is seatalk, not NMEA. You'll need 2 NMEA inputs for any device that needs position and AIS unless you have a multiplexer built into the AIS. AIS transmits at 38500 baud into the NMEA bus, and essentially all of the other NMEA talkers are slow-usually 2400 baud. So-ais nmea out can go to the garmin chartplotter nmea in-check to see if there are 2 nmea ins on the garmin, one dedicated to ais-that's how my simrad is set up. you can get a protocol converter, like the raymarine e50001 (I think that's the number) to convert between seatalk, serial, and nmea. The vhf is a listener, the autopilot has inputs-like waypoint bearing and heading that are probably nmea, and outputs-heading for use in radar/plotter overlays.

Frenchie3958 · Jun 1, 2010

NMEA 0183 Tips

Hi Jim,
Because I'm actually updating my VHF with a new model with AIS and already having ST60 Tridata, Furuno GPS/Sounder/Plotter, Furuno Radar, Laptop and my old VHF with NMEA 0183, I was looking for Information and found this information sheet:
http://www.actisense.com/Downloads/TechTalk/NMEA 0183/The NMEA 0183 Information Sheet.pdf
For the sentences:
http://www.gpsinformation.org/dale/nmea.htm#WPL
And for the Seatalk:
http://www.thomasknauf.de/seatalk.htm
:dance:

NMEA - Talkers and Listeners

Jim Seamans

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mcaswell

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chuckwayne

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Frenchie3958

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