Garmin in the weeds, an N2K gripe


Here’s some follow up on Russ Cooper, the Panbot who recently commented that he’s “spent >$10,000 to get an N2K coolant water pressure gauge that works…and still doesn’t have one!” Ouch. He has a legitimate gripe, I think, though I doubt the problem is unique to Garmin. You see Russ bought a Bennington 2275RLi with a Yamaha 150 that he’s using on a particularly weedy lake in Ontario. Whereas the Yamaha is sort of NMEA 2000 compliant, he put together the nifty system you can see above (bigger here) and diagramed below. But—cue the Rolling Stones here—you can’t always get what you want, as Russ explains:

After a lot of reviewing on-line, including your great site and several others, I finally purchased a Garmin 4212, GSD22, and connected that to a NMEA 2000 network via Maretron components to get engine data out of my Yamaha F150. One critical piece of data is engine coolant water pressure or temperature. My bay is extremely weedy, and I’ve been having frequent overheat warnings while slow trolling due to a plugged water intake. I figured that by monitoring the numbers, I could determine when a clog had occurred before the motor felt overheated, allowing me to get the clog cleared (by simply turning the motor off for a few seconds.)
   Garmin said it supported displaying NMEA PGN 127489, which has within it the fields for coolant water. Yamaha’s ECU puts it into the PGN via an add-on water pressure sensor. So, I figured I could do what I wanted. Well, turns out Garmin doesn’t display all of the fields in PGN 127489. No doubt this is true of other PGNs also. Because of this problem I have had to purchase an additional MFD in the form of a Yamaha digital tachometer to be able to display coolant water pressure {in less than satisfactory bar graph form}.

   So, now my suggestion. NMEA certification for display devices should be based on a more rigid standard. If a device claims to display a PGN, then it should be able to display all fields within the PGN. If it merely claims to display specific field(s) in a PGN, then that should be their certification level and NMEA should insist that the vendor make that fact clearly known to buyers. For example, Garmin does not advertise what fields they support, only what PGNs they pick fields from.
   I don’t know NMEA’s reasoning for grouping fields within PGNs the way they have, but whatever it is we have to agree that a PGN represents a collection. It should not be one collection on one vendors display, yet a different collection on another’s. If there’s an issue with specific fields; either that vendors feel they aren’t being requested or that they’re difficult or cumbersome to accommodate, then NMEA should reconsider what PGN they’re in.
   All I know for sure right now is that claims of certification and ability to display specific PGNs is false and misleading to the average, nay even the expert, consumer. This problem is caused by NMEA certification and/or their lack of clarification over what certification means. Since N2K fields are vastly more important than PGNs, vendors’ lack of informing their customers as to what fields can be displayed is leading to purchases which fail to satisfy expected consumer requirements.

Russ Cooper N2K diagram

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.

12 Responses

  1. Mike says:

    I see the Super SIDEBAR is advertising on Panbo. I’m the proud owner of one and so far it’s Ab Fab.
    exactly how to corral the bottles without wasting too much space. took a bit of “prototyping”, but at this point, i’d have a mutiny on my hands if the Super SIDEBAR suddenly disappeared.
    Although i find myself chagrined by defending NMEA2000, the problem of “what’s in the sentences vs what gets displayed” is hardly a failing of NMEA2000. that problem has been around as long as any other problem. The expectations set by the NMEA2000 propaganda may be exacerbating the disappointment, and if so, that’s self-inflicted, but it’s unfair to ding NMEA2000 for the industry’s failure to think about what it means to display the data (whether from NMEA2000 or 0183) in a manner meaningful for maintaining “situational awareness.”
    keep up the great work!

  2. Dan (b393capt) says:

    Time for an analogy …
    If a vendor represents they are selling a VGA compliant computer monitor (for example), but delivers a product that receives VGA but excludes displaying the last 10 rows of VGA pixels on the bottom of thir product, I would say that it would be the manufacturer that should get dinged.
    If an industry body defined VGA compliance and/or made certification possible without showing all the 800×680 pixels of VGA resolution (e.g. analogy to the content of the PGN), I would say that the standards body should get dinged (also).
    Therefore … I would have to agree with Russ …
    “This problem is caused by NMEA certification and/or their lack of clarification over what certification means. ”

  3. Kees says:

    That’s exactly what happened 20 years ago in the computer industry. IBM came out with a VGA monitor (640×480, not SVGA = 800 x 600) and from there on everybody invented ‘new standards’ that meant that it was hit-and-miss to find out which resolution and refresh rates your combination of CRT and video card would run at.
    They got it ‘somewhat right’ eventually…
    Why would the marine electronics industry be different? At best, in a few years, we’ll see better interop. At least in 2008 we can actually -get- NMEA2000 equipment from many manufacturers, which is already a huge improvement from a few years ago.

  4. Sandy says:

    What a FABULOUS install! Hats off to Russ Cooper!

  5. Russ Cooper says:

    First, thanks Sandy, but honestly, the hats off really needs to go to Ian and the guys at Fenlon Falls Marine who did the installation. I designed the network, but overlooked the fact the 4212 wouldn’t fit into the space I had…so they figured out how to cram it in there and make it look sweet…;-] We’re going to redesign the top of the console during the winter.
    As far as analogies go, perhaps that’s one of the most important reasons I’m peeved. I’ve been in the PC field since 1978, so I know precisely what they’ve gone through too. Did these N2K certifiers and vendors come to us just recently from another planet? One where they never experienced our history?
    There’s absolutely no reason we have to shoot ourselves in the foot over N2K just because we’ve done it over video displays for the last 26 years (because don’t think its stopped yet, think nVidia vs. ATI.)
    If the only problem was that I couldn’t get the Coolant Water Pressure to display as a gauge on the gauges screen, I wouldn’t be griping.
    At the heart of the issue, IMO, is that any vendor producing an N2K MFD today **knows**, with certainty, their MFD might be on a network with a device they’ve never seen (or firmware they’ve never seen for a device they have seen.)
    Garmin, like other vendors, offer the ability to place a single field of data on a screen (in the picture above its the list of numbers down the right side of the LCD.) You press the corresponding button and are presented with a list of “groups”, which (I believe) are Garmin tailored PGNs. From each you can then select the values that Garmin supports. On a 4212, some appear as numbers, others as small slider graphs.
    Every PGN Sentence carries with it all that is required to display it; what it is, a value (and detail as to whether that’s a single value, or a value in a range, etc…) Garmin, and all MFD vendors, should be simply allowing us to choose any Sentence on the wire. If they’re known to Garmin, Garmin can do something extra/special/whatever it is they think they need to do with it. If not, then just deliver the Sentence description/value…period.
    If Consumer Reports told you the new TV you were buying would do all VHF and UHF channels in the U.S., and you plugged it in and found it did only VHF channels 2-10 (not 11-13), and 14-51 (not 52-83)…you’d be miffed. Miffed at CR for not warning you, and miffed at the vendor for not knowing which channels they could get.

  6. Mark Max says:

    I have a Garmin 4208 and was hoping to connect my new Crusader 5.7L MPI engines to the Garmin. Found out that although Crusader says they are NMEA2000 compliant, they make no cable to tap into a NMEA2000 network.
    Based on your experience, any hope of getting the Crusader gauges displayed on the Garmin? Thanks

  7. JonnyBoats says:

    I can’t help but think that situations like this are exacerbated by the fact that NMEA 2000 is not truly an open standard, and by that I mean one promulgated by an internationally recognized standards body like ISO. If the standard was freely available at no cost and all users were permitted to make public comments and suggestions, I believe we would have fewer issues like this.
    As things stand now, access to the standard is expensive, well beyond the means of many if not most marine dealers ( ).
    What we have is what we are told is a great standard, trust us on that since we can’t let you read it for free. Further there is no independent certification that products meet the standard (like UL for example), we will do the certification ourselves, trust us on that also.
    If a consumer has an issue, how could you possibly know if the product meets the standard if you can’t even read the standard?

  8. Sandy says:

    Consider who the NMEA members are, and who serves on the committees. Consider who pays the committee members, and provides their benefits.
    I find it amazing that something this close to an open standard could come out of all that, and am grateful for the progress they have made.
    But anytime a product comes close to introduction and an N2K compatibility issue arises, the decision to postpone delivery to spend more money on development, or even retool, is made by company upper management in the light of profitability NOW, not two years later.
    Its the public voices, like Ben and Russ, who can reach those frequently myopic decision makers.
    So, Russ, do you mind kissing a lot of babies? We could write you in for President! (No, Ben, we need you where you are.)

  9. Russ Cooper says:

    Mark Max,
    You’ll have to contact Crusader and ask them if they can be interfaced to any marine network. If they can, which one(s)? Is their ECU used in any other brand of motor, maybe that vendor has a cable? You might contact Maretron directly, they may not be allowed to list a product they actually have on their site (because some vendors don’t want Maretron to say the vendor’s product is N2K compatible.)
    If I could become President Arnold would be really peeved…I’m Canadian…;-]

  10. Chris Moore says:

    We have made the connection from Command Link for our F150s to Garmin 4212 via added Yam multi hub and Mare003. First 30 minutes out, we got our fuel management readings on the Garmin. Then one engine Tach stopped giving us RPM numbers. (display was still illuminated. I checked our connections to be sure. Then other tach same thing. We shut down and restored our pre-Mare003 connections and upon startup, got RPM numbers again. Any thoughts? Thanks!

  11. Russ Cooper says:

    I’m going to take a wild stab in the dark and suggest that the problem is the Yamaha hub. I am assuming you have only the one hub is that correct?
    If it is, then the problem is that your network is now not properly terminated.
    I’m sitting here looking at the Yamaha Command Link Rigging Reference Sheet/Outboard Rigging Guide/ Wiring Diagram. It doesn’t give me part numbers for parts that are included with every Command Link network, so I will use the term they have on the diagram and put that in quotes here in this response.
    The Yamaha “Main Bus Wire”, when used in a single hub configuration, includes a “Single hub assy (with resistor)” connector that connects to the F150 ECM. IOWs, there’s the engine, a 4P connector, a “Single hub assy (with resistor)”, then a (“Main bus wire”) to the hub. The hub itself has another “in line resistor” thereby providing two terminators for the Command Link Network/N2K network.
    When you replaced the “Main bus wire” with the MARE-003, you eliminated the terminator at the motor.
    If you look back at the diagram of my network, I have a terminator before the connection of the MARE-003 to the main N2K bus.
    A Yamaha hub is nothing more than a series of N2K Tees with a spot for power to connect and an “in line resistor”/terminator. I doubt that the “Single hub assy (with resistor)” from the original “Main bus wire” connected to the engine can be put into one of the slots in the hub to turn it into an “in line resistor.”
    The easiest solution (albeit possibly the costliest) would be to replace your Yamaha hub with N2K tees. M/F Tees can be connected to each other, no need for cable in-between. A Maretron PowerTap Tee gets put in the middle somewhere, but note that this is a F/F Tee (unlike every other Tee they supply) so for terminators you’ll want 2 x Male terminators.
    You need 1 Tee for each device/gauge on the network.
    The other option is to install a 2nd Yamaha Hub. Plug the MARE-003 into this new hub, and your original “Main bus wire” (minus the resistor from the “Single hub assy (with resistor)”.)
    Since the 2nd hub will have its own “in line resistor” this should properly terminate your network.
    If my assumptions have been wrong…sorry…;-] If you can provide a bit more detail about what you have I’ll make better assumptions.

  12. chris says:

    Russ. I somehow missed your comments and thank you very much for your time.
    Last day of the year now, I am not using the command link to garmin mnea2k set up. I have what you wrote. An extra Yamaha multi hub,short main bus wire between them, resistor at end of second one and the mare 003 connects the second one to Garmin 4212. I have twin engines,so no room on the original multi hub. Andy at Maretron Support at Maretron tells me it should work.
    This set up fails after working all or in part within a few minutes of running. I get one tach on the garmin and some engine data. My boat tachs will eventually go blank. At that point, I shut down and reverse the wiring to command link only and get my yam sqquare tach readings again.
    Garmin wrote me “‘A NMEA 2000 network does require a backbone and power to operate
    correctly. I have attached a document and diagram that helps explain the NMEA 2000 connections needed for connecting your NMEA 2000 engine data
    to your Garmin GPSMap 4212.”‘ the diagram is of Ts and connectors and makes no use of the Yamaha hubs.
    If this is the only option, I am scrapping the idea, no real need to have the display on my Garmin. I wanted fuel numbers on the screen since it would be easier to read. And the garmin dash board display is nice, but in reality, i want my chart and sonar up.
    My last thought is to power the second hub also. I would need to purchase the Yam power cable. Maretron told me that is not necessary, since the first hub has power to it. The failure acts as though it doesnt have enough power.
    Happy new year.

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