SC20 Sattelite Compass Connection

[remotecaptures]

I'm looking to finish off my radar setup by connecting a SCX20 sattelite compass to my Navnet 3D MFD12 and DRS12a. I can connect my SCX20 and my DRS12a together using a NMEA 2000 backbone. Do I need to also connect my DRS12a to that NMEA 2000 backbone? It's unclear to me if the DRS12a needs the sattelite compass data, or if the data is shared via ethernet cable through the PSU-012, or if it needs to be conencted to the NMEA backbone.

I haven't run the system but as of now both the DRS12a and the MFD12 are connected to the the PSU-012 with an ethernet cable.

 

[Johnny Electron]

You would connect the SCX20 directly to your main NMEA 2000 bus. The radar has a CanBus connection for attaching items like the GP330B for convenience but in general, I don't recommend using it. It is better if your GPS data is dropped to your main 2000 network. At no time should the radar CanBus connection be wired to the NMEA 2000 bus. They are two different animals. The radar will get the heading it needs for ARPA via the main NN3D MFDs after they see the data on the Main NMEA 2000 bus. You would not make a connection between the SCX20 and the radar.

 

[remotecaptures]

Thank you for your explanation. This was explained to me once by someone at Furuno but I didn't fully understand it. I think I understand what you're saying, which is to connect the system in the same way as this diagram that I made:

I appreciate your time you took to respond and your experience. I'm here to learn and connect up my system and it's hard to convey tone over writing on the internet so know that I'm apprecaitive of your time and experience and I don't want continued questions to come off the wrong way.

As I understand it many devices support both NMEA 2k and CAN including Furuno so while I can add a NMEA 2k backbone for the sole purpose of connecting the SCX-20 to the the MFD12, it will cost be $200 in NMEA cabling, extra cable routing, added points of failure, additional space for bus bars, etc. You can see why I am trying to avoid that route.

What is wrong with the CAN connection in the DRS12a? Isn't the purpose of that CAN connection to connect devices like this directly? I'd love to learn from your experience, I'm guessing I must be mis-understanding the documentation but would apprecaite help clearing what I think the Furuno documentation says, which is that I can connect up directly to the DRS12a, and the advice to use a NMEA 2k backbone.

1) These two pictures from the Furuno CAN bus Network Design guide lead me to believe that you can connect a Nema 2000 device such as the SCX20 to the DRS12a directly:
Furuno CAN bus Network Design Guide






In the SCX20 manual they suggest that the CAN bus is NMEA 2k compliant:


Lastly, in the DRS12a radar they have a conenction labled "NMEA 2000" connection.




Much Apprecaited,

Pete

 

[Johnny Electron]

NN3D is an older system and the SCX20 wasn't even thought of during it's day. That connection in the radar worked for either the GP330B or the SC30 way back when. While it might work with the SCX20 there is most likely information that would not port down properly. The radar "bus" is networked down along with the radar data packets. While that connection would still work for NN3D and TZT series one; it totally won't work when upgrading to TZT2 or TZT3. That feature is obsolete and not inside any of the newer DRS units. It is best not to start using it now. The SCX20 will work best directly on the 2000 bus. Face it the idea okay to save running some wire but if the radar when out; you would lose the GPS/Heading to the boat also. With the NN3D, only one MFD connects to a 2000 bus. That one MFD send it over the Ethernet to all other units including the radar. If you ever find a NN3D system with more than one NN3D MFD on the 2000 bus it is wrong. While our newer systems, all MFDs go to the 2000 bus; for the NN3D the design was different.

 

[remotecaptures]

Ah that makes sense, thank you! I was in the middle of doing a complate re-edit of my post which I changed/saved only after you posted (didn't know you were replying at the time) so you can ignore the changes I made, your explanation makes sense. I have a bit of a unique case since I also run a garmin chartplotter for navigation/sonar and only use the Furuno/MFD12 for Radar and have no plans to upgrade but I will add in the 2k backbone system.

Thanks again,

Pete

 

[Johnny Electron]

Another good reason to have it on the 2000 bus where the Garmin can also use the good data. If connected to the radar, the data will be on the Ethernet and the Garmin will be left using lower quality/delayed data by 0183 or PGNs at a much slower rate.

 

[remotecaptures]

Hadn't thought to connect it up to the Garmin since the Garmin already has it's own GPS already but I like the idea of it seeing the heading data on that system too. Was toying with the idea of "isolated" systems, a furuno for radar and garmin for navigation in case one goes down but pretty unlikely to me that NMEA would be an issue. Thanks for the tip!