Connecting NMEA0183 to NMEA2000
Over the years there have been several iterations of how data is transferred between marine instruments onboard a boat and the chances are, unless you have a relatively new boat then you will probably have a combination of them.
So how do we connect them and share that data?
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The first thing we need to do is consult the instruments handbook/s or manual/s and check that our instrument does actually have the ability to use NMEA0183 as a data in/out. Is there a section in the manual on NMEA0183? If there’s nothing obvious in the chapter listing, try the index, if not look for a connectivity or communications section in the technical specs.
Assuming we have this information we can now carry on.
At this point we have to decide do I want this data on the network or can it go to just one instrument. If it only needs to go to one instrument and will never be required on the main network then there are other alternatives, although I’d recommend making everything available to everything else where possible.
What will I need?
Basically, for connecting NMEA0183 to NMEA2000, in a single instrument scenario then a simple NMEA0183/NMEA2000 gateway, pictured right, will suffice.
If you need to add more than one instrument to the backbone then you will need what’s known as a multiplexer, to handle several inputs.
Something to note here though, if either of the instruments is sending or receiving AIS data to the other then you will need to ensure that the relevant gateway or multiplexer can handle the AIS PGN’s, not all of them do.
The multiplexer I’ve linked on the left also gives you onboard wifi allowing you to use a phone or tablet for navigation with all the instrument data available to it.
Neither option should affect AIS that is already present on the n2k bus.
Most older instruments came with a multicore cable which may be carrying both the power leads and the NMEA data cables. It’s often easy to distinguish which is power and data from their relative thicknesses. Usually, the manual has, at the very least a chart, diagram, or paragraph detailing what the various cable colours are. Unfortunately, different manufacturers tend to use different cable colours.
Usually, you would expect to find at least the following on an NMEA 0183 instrument:
• NMEA DATA OUT +
• NMEA DATA OUT –
And if it can receive NMEA 0183 data then:
• NMEA DATA IN +
• NMEA DATA IN –
Once you have ascertained which cable is which, it is as simple as connecting the relevant cable to the relevant block on the gateway, they are usually very clearly marked in the installation instructions for the gateway/multiplexer.