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Analog wind velocity to STNG; help needed!

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Old wine and new bottles problem!

My masthead transducer provides analog output (three voltage waveforms 120deg out of phase) to determine wind angle and a pulse of voltage per rev of the anemometer to determine speed.

The instrument that calculates and displays the output is ancient and non-NMEA, so there is no chance of sharing w/v data with other NMEA devices. But I am about to install a new a/pilot which needs wind data if it is to steer to the wind!

So, using an Arduino micro controller, I have built a device that will read the analog output and output an NMEA0183 MWV sentence, complete with correct CRC checksum.

Now, I can take this output and parallel it to feed the chart plotter (NMEA0183) and then put it through an Actisense converter to create an NMEA2000 signal that (if I have read the book correctly) will directly interface with the Raymarine Evo a/pilot I am installing which requires an STNG backbone.

However, I was wondering if I can do the same trick - i.e. use an Arduino - to output the data in NMEA2000 protocol?

Problem is, the NMEA2000 protocol seems to be a bit of a secret!

Someone has told me that DeviceNet used by automobile industry with CANbus is the same as NMEA2000?

Either way - what is my next step to try and produce an NMEA2000 compatible output from my device.

(perhaps I should explain I am looking for a low cost solution simply because in a year or three I am going to need/want to upgrade my instrumentation and the problem will go away, so if I can make a short term solution that will work for a year or two that's ideal)

1 Reply

  • Graeme, it sounds like you've done some neat work already but messing with a homebrew N2K gateway is many quantum leaps more difficult. NMEA 0183 and 2000 are very, very different. Your best bet by far is to buy a gateway and even then I think you have a lot to learn about how N2K networks go together. DeviceNet, for instance, is NOT NMEA 2000, though NMEA does incorporate the DeviceNet "physical layer" (like cables and connectors). Both are related to CANbus but N2K is what is known as a "higher layer implementation" (like SAE J1939). There's lots of place to find better information that what you heard, like here...

    ...but frankly I think your next step is to study the Raymarine manuals about to install your EVO and either an N2K or STng cable/connector system.

    Sorry to play the wet blanket!