ST70, STng, & N2K, an ironic tale


So I hope yesterday’s goofy contest made a point about Raymarine’s STng cabling system. I do think the design has merit, particularly for production boat building, and there’s more of interest, like heavier gauge power wires, that I’ll get into eventually. But today I’m going back to the larger point that NMEA 2000 cabling is not that big a deal. As noted earlier in these ST70/STng experiments, the data flows easier than one might think given the different connectors and network names. What really counts is that the desired data is sent and received. I learned that vividly when the first Garmins could hardly understand any N2K PGNs (messages), despite having a standard NMEA 2000 connector, and now I’ve stumbled on an ironic reminder.

Though the Raymarine ST70, which I’m falling for, can display almost all of the data being sent by the various Maretron sensors in my test network (often as a number, graph, or dial), I was surprised that it would not see some numbers theoretically sent from the Raymarine E120. I set up a go-to waypoint, expecting all the values seen above…but all (except XTE) stayed blank! Was it the E not sending or the ST70 not understanding? One way to check was trying the same drill with the Garmin 5212, now updated to firmware 3.2 which does NMEA 2000 pretty darn well. And it worked, producing those numbers above.
   Better yet was observing all this using Maretron’s NK2 Analyzer (now official software, by the way). Below you can see part of the story, the glorious details of PGN 12934, Navigation Data, that’s being transmitted by the Garmin and displayed by the ST70 (full screen here). A similar screen from the E120 shows that it is not sending that particular PGN (but is sending 129283, XTE). Are you with me? Here we have three brands using NMEA 2000 together to pass data and troubleshoot a small (and easily fixed) issue that showed up within one brand. I like that! And never mind that it’s being done over a hybrid STng and DeviceNet backbone, which sure ain’t kosher but is working fine, at least in the lab environment.


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.

7 Responses

  1. Walt says:

    I had a ST70 installed on my sailboat a week ago and my tech connected it to my existing Maretron(Airmar) DST800 Smart NMEA2000 Speed/Temp/Depth Sensor. Unfortunately I had to tell him to take it back because the ST70 would NOT calibrate to my keel depth, speed, or temp offset settings!!!
    Raymarine told him that I had to install “THEIR” older style analog Airmar Speed/Temp/Depth Sensor with an expensive junction box to convert the data to make the system work. This was crazy to me and it would have meant drilling another hole and a haulout as well as the new equipment costs.
    Question for you: How can Raymarine claim NMEA2000 compatibility with the ST70 when it won’t work with other standard NMEA2000 stuff? Right now, I’m really frustrated and disalusioned by this NMEA2000 stuff. Indeed, what is the benefit if it won’t work with each other? My tech said that it is not a PGN issue because the data is there. It just isn’t right. He also said that the Raymarine ST70 has the exact same problem with their wind stuff as well.
    I liked the ST70 but, it was expensive and Raymarine tried to force me to switch over to their Seatalk NG stuff to make it work on my boat. I also had to buy adapter cables to make it work in my system. It was turning into a $2000 three inch display!!!
    Also, Maretron told me to be careful because the ST70 is NOT “NMEA2000 Certified” even though the Raymarine Staff claimed it was and Raymarine lists NMEA2000 compatibility in their brochures.
    What is with this crap? How can this happen? I thought that NMEA2000 was supposed to end all of this incompatibility! Instead, all of this is a show stopper for me with NMEA2000 and Raymarine products right now.
    My tech actually told me to bitch about this problem on your site.
    It is a coincidence that you are writing about some of the problems right now in the midst of my FIASCO with the ST70

  2. Jeremy Anwyl says:

    I have several ST70. They don’t not display waypoint data. They do not display water tank level data. They incorrectly display barometric data. (Although relative changes over time see OK.)
    Other data looks OK.
    My fix to get waypoint data was to plug one of the displays into my SeaTalk network.

  3. Russ says:

    I didn’t stay with you Ben. Did you resolve this? I concluded that you were able to display data from the Garmin on the Raymarine, but not Raymarine data on Raymarine.
    I think Walt has the real story here.

  4. Ben Ellison Ben Ellison says:

    Walt, Sharing data and calibrating sensors are two different things. We’re at the point with NMEA 2000 that the data sharing is going pretty well, sometimes even better across brands than within one (as illustrated in this entry). But there is little to no NMEA 2000 sensor calibration across brands.
    For instance, there is no way to setup a Maretron compass or weather station without using a Maretron display or N2K Analyzer software (via a USB100 gateway). Of course that’s true in the old world of NMEA 0183, too, so we’re not going backwards.
    In fact, it’s my understanding that the N2K Standard has a calibration facility built into it, but it’s not required, and hasn’t yet been used to my knowledge. When you think about it, it can’t be required. I talked to a Nexus guy about this in Miami and he said his company would never, ever open up its calibration routines as they consider them an important competitive trade secret.
    Now, keel and temp offsets are obviously a different animal, and I suspect the sort of thing that may be easy to set with a standard N2K PGN. Plus your Airmar DST800 is sold by multiple manufacturers so it can probably be calibrated by several brands of instrument.
    At any rate, I written about the calibration issue here and it’s fairly well understood by installers, I think. So I’d have been pleasantly surprised if the ST70 was able to calibrate a DST800.
    Interestingly, today a guy who somehow has a Garmin GMI 10 (color me jealous), wrote into Jack Rabbit and he says the manual claims it can calibrate “NMEA 2000” sensors.

  5. John says:

    The GMI 10’s have shipped I know a few different stores have them in stock right now.

  6. awboater says:

    I am that guy that posted at jackrabbit about the GMI10. I got mine at of all places, West Marine.
    The GMI10 Quick Start manual (you can download it on the Garmin website) states:
    Changing NMEA2000 Device Options:
    You can view information about your NMEA2000 devices and change available device-specific options on the GMI10.
    From the instrument screen, select MENU – SETUP – NMEA2000 Devices.
    You will see a list of all connected NMEA2000 devices. Select a device to see information about the device, such as the software version and the serial number.
    To change NMEA2000 device-specific options:
    While viewing the NMEA2000 device information, select CONFIG.
    Now; as I stated on jackrabbit, I don’t know if this is reality or not – since I won’t be installing the device in the boat for another month, so whether this feature is limited to Garmin NMEA200 devices, or other sensors is yet to be seen.
    By the way, the inexpensive Lowrance LMF200 does have a calibration menu – but I have not tried it with non-Lowrance devices so I don’t know how well it works in that regard.
    I am replacing my Raymarine ST60+ graphic with the Garmin, mostly because I can only get the thing to read Kts and Nm from my C-80. Seems that the C-80 only outputs Kts and Nm via Seatalk.
    Raymarine suggested using NMEA0183 to get Sm and Mph from the ST60+ graphic rather than Seatalk, which will indeed work. But at the expense of losing a lot of Seatalk-only data. What a hoot!
    For this reason, I decided if a manufacturer cannot even read their own data correctly, I’ll look elsewhere.
    While it does seem painful at this point with all of the incompatibilities of NMEA2000, I think that eventually NMEA2000 will allow the market place to force manufacturers into an open standard.

  7. Ben Ellison Ben Ellison says:

    Plugged a Garmin GMI10 into the lab N2K network today. It’s pretty cool, and I’m sure will get cooler with future software revisions. It could see and understand almost all the Maretron sensors, but would only configure one, the DST 100 (built by Airmar), and then only keel offset. But the thought is nice, and so is the ability to choose which source you want to use, and much more.

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