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Interface NEMA 2000...
 

Interface NEMA 2000 and SeaTalk ng  

 

Rich Gano
(@richgano)
Active Member
Joined: 8 months ago
Posts: 4
January 29, 2019 2:03 pm  

We have installed a RayMarine EV-100 wheel drive autopilot onto a sailboat which uses SeaTalk ng to network its various parts.  Wondering if we can tie in a NEMA 2000 based Garmin EchoMap Chirp 94SV?  


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Steve Mitchell
(@stevemitchell)
Member Moderator
Joined: 1 year ago
Posts: 86
January 29, 2019 2:17 pm  

If you have space on a SeaTalkNG 5 way connector or similar, you can purchase Raymarine part number A06045, which is a SeaTalkNG to NMEA 2000 (commonly called Device Net) and connect that to an existing NMEA 2000 backbone. Keep in mind, though, that if you have terminators already in place on the NMEA 2000 or SeaTalkNG network, that you'd need to diagram out the network and make sure you don't have too many terminators in too many places, among other things. I had a similar bridged network and discussed that in Grace's 5 part network. There are some other caveats in terms of length and such, so if you are combining networks, there's a bit more to think about there.

If you don't have an existing NMEA 2000 network/backbone, and only the 94SV, you can still grab the cable above, and maybe an additional drop cable of appropriate length to reach the 5 way connector or similar where it would plug in directly.

Editor, SailBits.com


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Rich Gano
(@richgano)
Active Member
Joined: 8 months ago
Posts: 4
January 29, 2019 3:09 pm  

Thanks, Steve!  We have the NEAM 2000 backbone and connection to the Garmin product as the result of having pulled it all from a boat totaled here in Hurricane Michael.  The drop from the Garmin plotter to the NEMA and the SeaTalk ng backbones residing side by side is only a foot or two.  The ST ng backbone has an empty white colored slot.  Is it going to be as simple as it looks - one end of the A0645 cable into the ST ng spare slot and the other end into the NEMA backbone?


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Steve Mitchell
(@stevemitchell)
Member Moderator
Joined: 1 year ago
Posts: 86
January 29, 2019 3:36 pm  

The only thing you need to verify is your termination count. SeaTalkNG and NMEA 2000 are essentially the same, and by connecting them with that cable, you're basically making one unified SeaTalkNG+NMEA 2000 bus. So if you have terminators on the NMEA 2000 bus already, and the little blue plugs that go in the SeaTalkNG bus as terminators, you need to make sure you only have two at the "ends" of the bus, depending on how things are laid out.

Editor, SailBits.com


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Rich Gano
(@richgano)
Active Member
Joined: 8 months ago
Posts: 4
January 29, 2019 3:55 pm  

Excellent.  We have only one termination on the ST ng bus now.  I am not sure what we have on the 2000.  Will have to check.  Thanks so much.  I hope there is full functionality of the AP to follow the Garmin route once this is done.

'nother quick note.  I see the Sensor Core (compass) of the RayMarine has a connectoin point for a "device" cable which came with the pilot.  Not sure what that could be used for.

Thanks again for your help.  I will report back how this goes in a week or two when my friend the owner gets back in town and we attack it some more.

Rich


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Ben Stein
(@ben-stein)
Member Admin
Joined: 2 years ago
Posts: 70
January 30, 2019 9:14 am  

One quick clarification.  The part number Steve referenced above (A06045) is a spur adapter, not a backbone adapter.  Raymarine uses different connectors for backbone (blue ends and stripe on the cable) and spur connectors (white ends and stripe).  Nothing coming off a spur should ever have a terminator on it, those should only be at the end of the backbone and NMEA-2000 spec limits any single spur to 6 meters and the total length of spur cables on the network to 78 meters.  Unfortunately, Raymarine doesn't currently make an NMEA-2000 DeviceNet to Seatalk NG backbone adapter though they say they're developing one.  

Because there aren't backbone converters and because Raymarine is also moving from Seatalk NG to DeviceNet I prefer to build an all DeviceNet network and then use spur adapter cables to connect Seatalk NG devices.  My current network was built with all Seatalk NG so I haven't taken my own advice and ripped out the whole network.  

Maretron has published a great cabling guide in general that discusses some of the general considerations for a NMEA-2000 DeviceNet network.  Because Seatalk NG and DeviceNet are electrically similar the considerations about length limits and the like are the same for both networks.  

 

Ben

This post was modified 8 months ago by Ben Ellison

Publisher, Panbo.com


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Steve Mitchell
(@stevemitchell)
Member Moderator
Joined: 1 year ago
Posts: 86
January 30, 2019 1:15 pm  

Good point on the adapter, Ben. Personally, I just purchase the blue SeaTalkNG backbone cable, chop one end off, and put a Maretron end on and continue on with that as my bus to NMEA 2000. 

My previous boat came with a moderate sized SeaTalkNG network, so ripping it out and replacing it with NMEA 2000 was not something I did initially. Eventually, I just chopped off the end of all of the SeaTalkNG cables, put NMEA 2000 ends on them, and removed the SeaTalkNG 5 port adapters completely.

Editor, SailBits.com


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Ben Stein
(@ben-stein)
Member Admin
Joined: 2 years ago
Posts: 70
January 30, 2019 2:37 pm  

What Steve describes is a great alternative if you're comfortable putting ends on the cable and in fact, I've had Raymarine recommend exactly this.  I've done it and it works well.  

Ben

Publisher, Panbo.com


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