I think it may be a case of needing to ask very specifically phrased questions of the manufacturers. If I were talking to Garmin I would say something like I see your GPSMap 2143 has a J1939 port on it, from there can I assume that it translates J1959 to NMEA 2000?

If I were talking to Cummings I would ask does your engine output J1939 or do you have custom PGNs for your engines? If they say we use pure unadulterated J1939 then you can probably assume that your Garmin with a J1939 port can use that data without a gateway. Or if they say no we have proprietary PGNs, then you must have a gateway. 

J1939 is a standard like NMEA 2000 and if the Cummings engine is outputting J1939 then any J1939 enabled instrument or display should be able to read the data coming out. They are all based on CanBus and NMEA 2000 and J1939 are customized versions of CanBus. They add information to the beginning and end of the string to identify where it is coming from and where it is going and how it should be used so it is like UK English vs US English vs AUS English Vs NZ English. They have their quirks but we are all speaking the same base language.

What year and model of QSC engines do you have? Have you been able to confirm they have J1939 available? 

Garmin has equipped their current GPSMap line with J1939 interfaces but make very few cables to go from the Micro-C connector to engine manufacturers connectors. There are myriad different connectors for various engines and I get the feeling the MFD manufacturers aren't super interested in getting into the adapter cable business. So, if you can figure out how to get the data to the MFD, the MFD can convert it. 

There are specialists like Maretron and Yacht Devices that make engine gateways and quite a few adapter cables. I own Yacht Devices U.S. so I'm most familiar with their products.

-Ben S.

Thx for comments. It is a 2010-era Cummins QSC 8.3. Yes we already have the old Smartcraft display up at the helm which presumably is reading CANbus data. so its not a matter of engine to NMEA2000, its more a matter of inserting the CANbus data from the smartcraft into the J1939. Garmin says CAN is a portion of their J1939 so Ben could be right in the idea that a complex harness is involved.

From what I read, I'm likely stuck buying a purpose-built gateway in order to make this work, like the one Panbo reviewed recently from Mercury "Smartcraft Connect"....

Thanks!

Ben, I have confirmed with a level 2 Cummins Tech that my QSM11's diagnostic port has both J1939 and J1708 in a round 9-pin Deutsch connector.  And my Garmin mfd has their J1939 port for engine display.  Does anybody make that cable or do I have to create it?  Also, I don't know yet if my fuel level sensors are going to be on that diagnostic port.  If not, then maybe I need a Yacht Devices sensor for analog resistance measurements to put the tank levels on my N2K backbone??  BTW, the level 2 Cummins guy was super responsive and helpful.

Thanks

I have two Yacht Devices interfaces, one each for my Cat C12 engines, along with the necessary J1939 Deustch adapter cables.  Works nicely.  Their website lists an adapter for Cummins also.  

https://www.yachtd.com/products/engine_gateway.html

@captmike2

I don't know of any off-the-shelf cables for the Garmin J1939 connector, so to use that you will have to make your own. In most instances, the fuel levels aren't run through the engine ECUs so you will likely need a separate sensor for that. But, you won't know for certain until you try it.

-Ben S.

Thanks Ben.  I was pretty sure that would be your response to both issues.  I'll be ordering 2 of the YD's with the Cummins version of the 9-pin Deutsch connectors.  One last question, though.  Do the engines broadcast their port/starboard designation or do I need to figure out a way to determine which is which once the data is on my N2K network?

Posted by: @captmike2

Thanks Ben.  I was pretty sure that would be your response to both issues.  I'll be ordering 2 of the YD's with the Cummins version of the 9-pin Deutsch connectors.  One last question, though.  Do the engines broadcast their port/starboard designation or do I need to figure out a way to determine which is which once the data is on my N2K network?

It's quite likely that your engines' J1939 networks are linked. If they're linked, the standard convention is for the port engine to be set to engine ID 0 and the starboard to engine ID 1. In this case your MFD will pkc up the engines without any intervention. Also, if this is the case, you will only need one engine gateway and wiring adapter. 

On the other hand, if the engines aren't linked, you will need two gateways. Also, when the engines aren't linked both engines will be sitting at engine ID 0 and you will need to configure the engine gateways to convert the ID of the starboard engine to 1. 

-Ben S.

There's more than one question here. 

One being are the engines using their own individual J1939 buses or are they networked together?  They could be either way.  My C12 are independent and not networked to each other.  I had to use two separate adapters and cables.  And I had to set each adapter to use a different network Instance ID, and then manually configure which one was port or starboard.  Only has to be done once.

If yours ARE networked together then you "should" be able to bring them both into a single J1938 port.  You would need nothing other than an appropriate adapter cable.

The Garmin online manual mentions being able to configure it to support more than one engine.  It would then be up to how your J1939 network is configured as to whether it would recognize them as both being present, and providing separate data.

What engine monitoring display do you have now?  

If you have double engine displays then you probably don't have a single CAN bus network between the engines.  The question would then become how to either combine the buses and feed them into the Garmin's existing connection.  Or if it would be possible to use just one engine into the existing J1938 on the GPSmap and then add a single YD interface.

Because there's nothing mentioned in the Garmin manual online about supporting engine data in from the NMEA-2000 network.

Ask Garmin if the 1243 (I'm assuming you meant that, not 2143) is able to display engine data from the N2K bus, or if it's only capable of displaying engine from it's own J1938 connection.  I wouldn't assume it'd be limited to only the J1938 connection, but vendors have done dumber things.

Posted by: @wkearney99

There's more than one question here. 

One being are the engines using their own individual J1939 buses or are they networked together?  They could be either way.  My C12 are independent and not networked to each other.  I had to use two separate adapters and cables.  And I had to set each adapter to use a different network Instance ID, and then manually configure which one was port or starboard.  Only has to be done once.

If yours ARE networked together then you "should" be able to bring them both into a single J1938 port.  You would need nothing other than an appropriate adapter cable.

The Garmin online manual mentions being able to configure it to support more than one engine.  It would then be up to how your J1939 network is configured as to whether it would recognize them as both being present, and providing separate data.

What engine monitoring display do you have now?  

If you have double engine displays then you probably don't have a single CAN bus network between the engines.  The question would then become how to either combine the buses and feed them into the Garmin's existing connection.  Or if it would be possible to use just one engine into the existing J1938 on the GPSmap and then add a single YD interface.

Because there's nothing mentioned in the Garmin manual online about supporting engine data in from the NMEA-2000 network.

Garmin supports more than one engine on their J1939 interface as long as they are both on the same physical J1939 network and addressed appropriately. 

I don't think that single or double engine displays will prove to be a reliable way of determining the network configuration. I've seen lots of engines with two displays and a single unified J1939 network. This is especially common with Volvo EVC. For whatever reason, it's more common to see Caterpillar installations without the networks joined. With modern engines, it's very common for manufacturers to implement throttle sync by networking the engines and comparing the J1939 RPM data. 

Lastly, without a doubt, the Garmin displays can accept NMEA 2000 PGNs 127488 and 127489 which contain engine parameter data. I haven't texted a mix of J1939 sourced engine data and NMEA 2000 sourced engine data but would be surprised if that were problematic.

-Ben S.

I hear you, and hope you're correct, but as I work with more N2K and CAN bus devices I've learned not to assume anything when it comes to vendor implementations when there's more than once data source present.  

@wkearney99 You're absolutely right that the less you assume, the less frustration involved. There's little consistency in any of this even with the same engines in the same boat. Things change from hull to hull, builder to builder and seemingly without any rhyme or reason.

-Ben S.

Bill and Ben, you've both left me in the dust.  My engines have a standard Cummins diagnostic panel with 2 Deustch connectors labeled Port and Starboard and the Level 2 Cummins tech that has been helping me sort our what data protocols my motors are using never indicated anything about whether they were linked together.  My engine data is displayed in 2 different ways.  I have electronic displays from Cummins that are using J1587 data coming through 2 separate & identical conversion boxes and I have OEM Sea Ray analog gauges that receive their data from a box that converts the J1587/1708 data into the analog signals to the gauges.  That same box is where the analog fuel level sender info gets sent to the fuel gauges.  That box has failed and there is no repair or replacement options, which is why I'm doing all this in the first place.  Thoughts??