N2K power question

[Jerry Woodward]

I just bought a Zeus 2 9", Vesper XB8000, and a BG 508 wind sensor with 20M of N2K cable. I plan to run the backbone down the mast and have drop cables to the Zeus and Vesper as well as a power cable, pretty straightforward. My confusion is that both the Zeus and Vesper have an independent power connection separate from the N2K connection. I thought that the devices were supposed to get their power from the N2K network. Are those other power connections only needed if you don't have an N2K hook up?

[alctel]

Nope, they have their own power source which needs to be attached.

Some stuff does draw power from N2K but it's small power drains like a GPS unit or electronic compass

[Jerry Woodward]

Ok, that makes sense, thanks.

[a64pilot]

You may chose to run an independent breaker for the backbone, that way when you have bus powered devices like my ST 60’s you can turn them off or on.
I believe the amount of total power that the bus can draw isn’t much, I have wondered how easy it is to overload.

[Jerry Woodward]

Yeah, I plan to have the N2K network on a separate breaker with appropriate fuse. But this raises an interesting question. Since the Vesper and Zeus are powered separately, will they talk to each other via the N2K network even if it is not powered on? I would predict yes, because they are sending and receiving data under their own power.

a64pilot, you have your ST60 hooked into a N2K network?

[a64pilot]

My ST 60 wind, ST 50 speed and ST 50 Depth are only hooked to the NMEA 2000 bus, nothing else except their sensors of course, they are bus powered. They daisy chain together and only one has a direct bus connection, although you can directly connect all three. I do not know if there is an advantage to direct connection.
It started when I had a Maretron wind sensor installed. The installer assured me he could make it drive my old ST60 wind, I was pretty sure he couldn’t but he was the expert, right?
Anyway, you can’t drive an old ST60 off of the bus, so I ended up with a new ST60 wind flanked by two old ST60’s. That worked but it wouldn’t give me true wind without the speed sensor and I didn’t like the way it looked so I replaced the other two as well.

I don’t know if the Vesper and Zeus will talk to each other without powering the bus, I too have a Vesper and a Zeus, but have never turned them on without powering the bus too.

[a64pilot]

I just tried it, it seems that without powering the bus that the Zeus and the Vesper do not talk. There were no vessels on the list in the Zeus while there were several on the Vesper, and I went to System and looked under devices and it did not list the Vesper, so I’m pretty sure you have to have bus power for them to talk.

[smac999]

it's not going to talk if you shut off the bus.