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David Pendleton posted 08-14-2013 11:54 PM ET (US)   Profile for David Pendleton   Send Email to David Pendleton  
It's been a while since I messed with NMEA devices, so I have a question.

I have a Raymarine Raystar 125 pushing NMEA into my chartplotter. This is done via a standard Raymarine junction box (sort of like a telco punchdown).

I have a new KVH Azimuth compass and I also want to direct its NMEA output to my chartplotter.

Can I just join all the input and output wires in the junction box, or do I need a multiplexer?

I'm guessing the mere fact that a multiplexer exists, I have my answer, but I was hoping to get by cheap and easy on this one.

Thanks all.

jimh posted 08-15-2013 10:10 AM ET (US)     Profile for jimh  Send Email to jimh     
NMEA-0183 is a point-to-point serial connection, not a bus or network. However, you can use one NMEA TALKER to drive several NMEA LISTENERS. But you cannot use two TALKERS to drive a single LISTENER; that is when a multiplexer is needed.

If your chart plotter has only one NMEA-0183 input, and you wish to have two TALKER signals connected to that input, you will have to get a NMEA Multiplexer. The Multiplexer will combine the two TALKER data streams into a single data stream, which you can then connect to the LISTENER in the chart plotter.

Many chart plotters have more than one NMEA-0183 input. What kind of chart plotter do you have?

David Pendleton posted 08-15-2013 10:02 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Thanks Jim. I have an older Raymarine RL70CRC. Come to think of it, my GPS receiver is using SeaTalk, so I only have one NMEA item to connect at this point (my compass).

In fact the manual states "Accurate heading data is required for MARPA and radar and chart overlay, and it must be provided on NMEA."

Problem solved, I think. Thanks for the information.

jimh posted 08-16-2013 12:51 AM ET (US)     Profile for jimh  Send Email to jimh     
I recommend you follow up with your inquiry on the excellent forum hosted by Raymarine for technical support of their products. Visit the website

You may have to register to post an inquiry. The Raymarine-sponsored forum seems to give excellent and very rapid replies to customer inquiries about Raymarine marine electronic devices.

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