Can Signal-K merge data from 2 or 3 independent NMEA2000 networks

[flpaoli]

If someone installs equipment on a boat with 2 or 3 independent NMEA2000 networks, not interconnected, but each with a wireless converter to WiFi, can a Signal-K server merge the data from them all?

Or is this setup impossible due to the lack of NMEA2000 to WiFi client hardware, or lack of functionality from Signal-K?

[Ryban]

I haven't done it, but I also don't see why it wouldn't work. Each data source should still get its own unique identifier.

[mcarthur]

I believe signalk can integrate from as many networks as you want. However, sending to specific networks may be harder (not sure). I have only one network though so can't practically comment.

[kaz911]

Originally Posted by flpaoli

If someone installs equipment on a boat with 2 or 3 independent NMEA2000 networks, not interconnected, but each with a wireless converter to WiFi, can a Signal-K server merge the data from them all?

Or is this setup impossible due to the lack of NMEA2000 to WiFi client hardware, or lack of functionality from Signal-K?

I don't know any reason for having 2 or 3 independent N2k networks?

If you have segmented networks - merge them with a bridge like the CZone Bridge or if you need filtering/blocking to lower the message count etc - then Yacht Devices YDNB-07 (https://www.yachtd.com/products/nmea_bridge.html)

I have 2 N2k networks - one "low power" and one "full-on" - merged by CZone bridge when I turn on the "instruments" circuit breaker. Everything using a lot of N2k power like displays are on the "full-on" "instruments" network.

The "low power" N2k network is powered via a separate battery and charger - giving me currently about 2-3 weeks runtime - with wind and speed sensors + a GPS receiver. That is then interfaced to an optional tiller pilot on our hydrovane. So worst case and just a tiny bit of sun we can comfortably stay sailing in case of most major systems failure. (Sun for charging tablet/phone for charts/routing)

I will add a 3rd N2k segment & bridge soon - to isolate mast mounted items. Radar will be put through an Ethernet -> Optical -> Ethernet gateway as well. That should keep most potential lightning damage isolated from rest of systems.

[barcoMeCasa]

Should be able to, each with its own connection. These are the sources which signalk accepts for n2k >

[maine-cruiser]

Originally Posted by flpaoli

If someone installs equipment on a boat with 2 or 3 independent NMEA2000 networks, not interconnected, but each with a wireless converter to WiFi, can a Signal-K server merge the data from them all?

Or is this setup impossible due to the lack of NMEA2000 to WiFi client hardware, or lack of functionality from Signal-K?

There is a Signal-K Discord server where you can pose this question and hear back from the developers.

Bill

[flpaoli]

Originally Posted by kaz911

I don't know any reason for having 2 or 3 independent N2k networks?

(...)


So worst case and just a tiny bit of sun we can comfortably stay sailing in case of most major systems failure. (Sun for charging tablet/phone for charts/routing)

I will add a 3rd N2k segment & bridge soon - to isolate mast mounted items. Radar will be put through an Ethernet -> Optical -> Ethernet gateway as well. That should keep most potential lightning damage isolated from rest of systems.

Thank you @kaz911, that's exactly the use case I was imagining, improving lightning resistance.


The theory is that if I have electrically segregated N2k networks, each with it's own battery charged via a DC-to-DC charger which can be 100% electrically disconnected through 2 switches, the potential damage from lightning can be severely reduced.


Makes having a Signal-K server a really interesting element in the boat network.


@kaz911, I did understand that's not exactly what you have. You electrically connect the networks through the bridge via a circuit breaker. Seems like you've figured out that it does isolate the potential path of lightning. In my approach the air/Wifi and decently robust switches for the DC-to-DC path would be expected to do that.

[flpaoli]

Googling around found this thread, related to lightning damage mitigation: https://www.cruisersforum.com/forums...-270317-3.html


The key thing I believe I'm thinking different from the diagram in that thread is using dumb physical disconnects and Wi-Fi to really isolate each segment.

[kaz911]

Originally Posted by flpaoli

Thank you @kaz911, that's exactly the use case I was imagining, improving lightning resistance.


The theory is that if I have electrically segregated N2k networks, each with it's own battery charged via a DC-to-DC charger which can be 100% electrically disconnected through 2 switches, the potential damage from lightning can be severely reduced.


Makes having a Signal-K server a really interesting element in the boat network.


@kaz911, I did understand that's not exactly what you have. You electrically connect the networks through the bridge via a circuit breaker. Seems like you've figured out that it does isolate the potential path of lightning. In my approach the air/Wifi and decently robust switches for the DC-to-DC path would be expected to do that.

My power to the backup network is on a separate isolated power network with independent DC minus - and isolated DC charger. Rest of boat runs off 24V mains - but without isolation so everything else is "grounded" together. And 12V for N2k primary is still run through an DC-DC 24->12v converter - but NOT an isolated converter. (So shared DC minus with 24v system)

N2k bridges are optically isolated with individual power from "both sides" - so each side of the bridge has its own "power supply" to power the optical chip. Primary side is powered from Primary side - and secondary side is powered from secondary side's N2k network.

Optical N2k isolation on a chip is NOT full lightning protection - but it gets you a lot of protection as long as you protect the power supply to the N2k network(s).

On the power feeds you can add lightning suppressors with direct path to ground (preferably not DC minus) - the suppressors have high voltage diode protection and a "leak" path to the ground. (Usually a big exterior grounding plate).

I'm using my Ex. SSB Dynaplate as main path to RF ground and N2k shield etc. as we no longer have SSB installed - and the SSB Dynaplate has a big "virtual surface area". The big virtual surface area helps lightning consider that an easy way to "ground" without passing through the engine ground. Both are "ground" connected to the water - but the large virtual surface area of the Dynaplate is bigger than the shaft/prop or sail-drive surface area so lightning might find that preferable. (but inspect your dynaplate for water leaks post any lightning strike... with plugs ready at hand...)

You can also get Ethernet lightning suppressors - but my primary choice is to convert ethernet to fully optical and run from mast foot to ethernet switch via a small Eternet to Optical switch. No power can travel over the optical.

As I have 2 full/complete N2k network backbones running side by side - 1 main and 1 backup (used for the low power network) - if something happens to my primary - I can re-route my entire backbone in 10 minutes by moving connectors. I also carry 50m N2k wire as spares and box of field attachable connectors.

My 3rd "N2k" network/backbone will be just for mast N2k items - so it only sits close to the mast - so backbone is about 30cm long with T's and terminators and N2k bridge.

But problem using Signal-K as your aggregator and distributor is you "wire" for single point of failure. I would not do that unless you have replacement on board for the Signal-K server with full backup of your configuration every time you make changes.

Remember running on WiFi - you have additional devices with .. antenna.. which are all great at catching stray impulses from lightning strikes. It takes a LOT less to damage a WiFi circuit than it takes to damage wires IF you have a good wire path (shield) to ground.

My solution is NOT perfect - no solution ever is. Lightning has a way to find unexpected paths.

And I'm still learning so take the above advice with caveats that I might be wrong.