I need a NMEA Lesson

[MichAngler]

I’m sure I’m not the only one that doesn’t know enough about NMEA Networks and what some stuff does and when you might need them

Now I have the basics you need power for the network and the power as well as any device needs a T connector and backbone cable plus you need terminators on each end of the string of T connectors (1 Male – 1 Female)

Next correct me if I’m wrong

Backbone cables are also extension cables yes?
NMEA 2000 Multi-port T-connector is just a pre-made tree of T connectors yes?

Now there are some connectors that I have never seen mentioned and I’m curious as to their purpose can someone please explain what these connectors do and when you would need them

NMEA 2000 Power Isolator

NMEA 2000 In-line Terminator

NMEA 2000 Field-installable Connectors Male/Female




Attachment 480771

[fishin couillon]

For the record, i'm not an expert on this marine stuff so here what i say:

Backbone cables are also extension cables yes?

You could describe the extension cable as that....same difference

NMEA 2000 Multi-port T-connector is just a pre-made tree of T connectors yes?

Yes....

Power Isolator Tee - I see that Garmin has this type of Tee but dont see it with Lowrance, i would think that it isolates power to just the Tee......per Garmin website this is how it describes this particular tee: Use our power isolator to ensure sources that could power the bus are separated properly during installation of the NMEA 2000 network


In-line Terminator - same as the male/female terminator that are on the end of the networks, this one is in-line and can "complete" the network......per Garmin website: Use our inline terminator between the backbone cable and your compatible device to correctly terminate the network.

Field Installable - those look like if your end got cut off or you had a some NMEA cable but no ends you can use this to make the ends.....

[MichAngler]

OK so I get the Field-installable Connectors they are so you can splice or cut to length a cable

But the other two I still have questions

So the Power Isolator is to isolate devices that have their own power so you don’t feed power to the network from this device when you turn the network off?
Are their devices that require their own power that could back feed the network?

Next the In-line Terminator
I can see having a T connector with a built in terminator it would save you some money and time but it looks as if you can still make 3 connections?
And it’s cheaper than a normal T connector so this one really has me confused

And one last question
What devices might you use in the boat that would work off the “ANT” wireless network?

[Bill Reynolds]

I am drawing strictly on experience but offer my understanding of the two devices:
Power isolator:
1) if my memory Is correct, the old Lowrance LMS series chart plotters powered NMEA networks directly from the unit. This series did not have internal GPS antenna so had to rely on external pucks connected via NMEA 2000 and powered by the chart plotter.
2) I saw a NMEA diagram of a Yacht that had many devices and sensors spread across multiple decks. There were multiple power sources and instances where various parts of the network needed to be powered down while others remained powered.
Inline Resistor:
1) On this same Yacht, there was a radar puck mounted very high on a mast and they had an inline resistor in the cable.
2) Ranger built me a new hull and changed over my motor, tm, electronics etc and in the process, installed an inline resistor in the NMEA cable to my Point-1 mounted on the back deck. When I picked up the new boat, there was a box with several NMEA components and cables that they did not use. It took me a while to figure it out but their method worked as well as mine.
You may be able to connect a device to either the end or top but not both; don’t know.