DY NMEA 0183 to USB, looks handy

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

16 Responses

  1. Rick says:

    49 bucks for a piece of wire? Could someone make one by cutting off one end of any USB cable>

  2. Anonymous says:

    How is this different from the squillions of RS-232 to USB connectors that already exist (besides the bare wires instead of DB-9 connector)?

  3. Ben Ellison Ben Ellison says:

    Click on the photo, Rick; you’ll see there is a miniature circuit board built into the USB connector. As Anonymous notes, this is an RS-232 to USB serial adapter. I guess the connection can be done a little cheaper with an office style adapter, but you may need to wire a db-9 connector, you’ll end up with a another lump or two in your system, and not all adapters work well with NMEA 0183 anyway. This design is very clean and purpose built.

  4. Evan says:

    This looks very similar to the TTL-232-R-5V (low power) cable I purchased for $20 from an electronics parts supplier. The cable I purchased is made by FTDI…
    …who also make a RS232 level cable and versions which they do not have pictures for that have the bare wires of the above products.
    FTDI makes these cables for resellers with their packaging specifications.
    I use these adapters for my NMEA multiplexor and one to control my ICOM-M710.
    Digital Yacht’s $49 is not a bad price for a retail packaged version, but if you are in the marine electronics installation business you can do better by buying the FTDI adapter, and you can get bulk pricing.

  5. GPSNavX says:

    One benefit I see with this cable/adapter is it will handle the differential signal that is true NMEA-0183 that most marine instruments use. While some “office” adapters can handle it, not always..

  6. Adam says:

    FTDI shows up all over. When I plugged in an Actisense NDC-4 today (it comes with a USB connector), Windows asked if I wanted to install the FTDI drivers.

  7. Shane says:

    As NMEA is RS422(5volt differential async), why not simply use a USB to RS422 converter ?

  8. Terry says:

    Nice, no longer is there a need to specify; “You need a laptop with a serial port” or the tiresome act of warning people that if you buy that db9-usb adaptor from Best Buy and it doesn’t work…you’re stuck with it.
    We always had great success with the db9-usb adaptor from Sea Level, though they were $90US/ea.

  9. Andy Campbell says:

    If this converter is not galvanically isolated in both directions then its use in a marine environment could prove to be both problematic and costly.
    Ground loops between PC/laptops and NMEA 0183 networks are quite easy to create and without isolation they can result in poor communication when small, and real damage to the PC/laptop when larger, or when used for a long period of time.
    Isolation is the only way to guarantee good communications and no risk of damage.

  10. Chris Ellingsen says:

    The product now appears on the Digital Yacht website under PC Accessories, and it seems that the entire USA website is just a redirect over to the UK site.
    Of course the product is more than just a standard USB to Serial adapter, there are also the NMEA differential drivers and (hopefully) opto isolation between the USB serial chip and the NMEA line drivers.
    The description on the website does not specify opto isolation but most such devices include it. It would be nice if they included a bit more technical details on the website description.

  11. steverow says:

    Just to avoid confusion, Digital Yacht, Cactus Marine and Marine Electronic Services (Bristol UK) are all part of the same group.
    The US Division operates out of Newburyport under the Cactus Marine name but it is a recent startup.
    MES has the biggest name in the UK and handles all DY stuff,
    Cactus USA are Here:

  12. Al Thomason says:

    Nice catch Evan,
    Looking more at the FTDI site I found this:
    Isn’t that this device?
    The FTDI site has a good data sheet, including schematic: http://www.ftdichip.com/Documents/DataSheets/Modules/DS_USB_RS422_CABLES_v120.pdf

  13. Andy Campbell says:

    Great find – that proves that DY are just re-badging an FTDI product, and more importantly there is absolutely zero opto-isolation. I didn’t think it was physically possible to fit all the required opto-isolators in to that tiny mould.
    There is no way any sane person could recommend use of a non opto-isolated USB adapter product in a Marine environment.

  14. Evan says:

    I am not positive they are using the FTDI product or not, but it is a distinct possibility.
    It is possible to fit the opto-isolation in that size of package if you are using surface mount technology. The miniaturization of components with surface mounting on four layer boards is absolutely amazing. Having said that, I have no idea whether they have opto-isolation in their product.
    For my own use, I have opto-isolation (not surface mount) components on the board that I connect the FTDI cable to, and then I have connectors that lead out to my marine equipment. Very simple circuit.

  15. Evan says:

    p.s. I did review the schematics and component datasheets for the FTDI product ( http://www.ftdichip.com/Products/EvaluationKits/USB-RS422.htm ) this resembles, and there are no opto-isolation circuits in the FTDI product.

  16. Mike says:

    I am wanting to interface my MNEA 183 devices to a Raspberry Pi running SignalK. I see it comes with Windows/Mac/Linux drivers but no mention of SignalK. Will this adapter require specific SignalK drivers to work?

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