NMEA 0183 wiring, why it bugs me

NMEA 0183 mess

OK, I admit that at least half of the hideous mess above is the fault of yours truly, being sloppy with a temporary install, in this case interfacing a DSC VHF, a GPS, and an AIS receiver all to a Garmin 3210 (possible because it has two 0183 ports, plus a NMEA 0183Northstar Stylespecial Garmin GPS port). But I also blame the standard itself, or non standard really, since there is no common plug, let alone standard wire colors (so you’re delighted to come across nice labelling like Northstar’s at right), or even a uniform nomenclature. Plus the typical bare wires are fine gauge, making them hard to handle and hard to secure strongly. Finally, the variable way the negative side of an 0183 data IN or OUT wire pair works—sometimes wired to its negative OUT/IN opposite, sometimes wired to ground, sometimes not wired to anything—further confuses things, and often  means that there’s a partial crossover between the power connection strip (upper left) and the data strip. The photo below, and bigger here, shows how this can all be neatly done, in this case by pros, but it’s still a bit fragile, I think, and it’s going cost you time or money. The chaos and complications of NMEA 0183 wiring make the rugged NMEA 2000 combined data/power cable scheme look very, very good.

NMEA 0183 pro job copyright Panbo

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Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now excited to have Ben Stein as very able publisher, webmaster, and editing colleague. Panbo is going to the next level in 2019 and beyond.

4 Responses

  1. Jim HebertJim Hebert says:

    I completely agree with your observations. It is usually not too difficult to connect the (+) phase outputs to the appropriate inputs, but handling the signal grounds or the (-) phase outputs and inputs can be very confusing. I suspect that some manufacturers have provided unbalanced or single-ended outputs yet have marked the signal ground with a (-), implying a differential output and adding to the confusion of how to properly connect them.
    When you add other variables to the interconnection, such as baud rate, it can be come even more frustrating.
    My current NMEA-0183 interconnections resemble yours, although slightly neater.

  2. Mike says:

    NMEA-0183 does specify a baud rate so that should not be a variable. Most of the time you can wire the NMEA (-) to ground on both sides, the transmit and the receive units, that is unless isolation is actually required (NMEA is supposed to be opto isolated.) Then one wire is required from the power strip to the comms strip and you can connect the negitives of all units into it. NMEA 2000 might not be the answer that people think as it is not really widely supported even now, there are still many units without it and of course all the existing units out there. NMEA 0183 will be with us for a long time to come I think.

  3. ibsailn says:

    I am about to rewire our NMEA-0183 system to add a multiplexer for wind instrumentation and future AIS support and am having a bear of a time finding appropriate 4-conductor shielded cable. I have 2-conductor shielded for my NMEA listeners, but I need 4-conductor for the 2-way communicators (computers & VHF Radio) and I can’t seem to find it anywhere anymore. I could go with un-shielded in which case I would probably choose to use CAT-6 UTP cable as at least the twist rates will cut down on interference, but I would prefer a sheilded cable as it runs by the SSB and VHF radio’s. What do you guys use for old school NMEA-0183 systems?

  4. CharlieJ says:

    ibsalin-
    Pacer Marine stocks two pair cable with an overall shield p/n: M22/2PRF and a two pair cable with each pair individually shielded and an overall shield p/n: M22/2PRIF
    Contact Pacer Marine at 941.378.5774 and ask for Bill Ensinger…tell him Charlie sent you!
    Charlie
    JTB Marine Corp.
    http://www.jtbmarine.com

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