Victron VE CAN to NMEA 2000

[PaulRainbow]

Off topic - sorry - have you ever used the Garmin wireless units that just connect to wireless devices, ie iPhone or iPad? I know there’s obvious issues with than but as a secondary radar on a flybridge.

I have two Garmin plotters on the flybridge, a GPSMAP1223 and a GPSMAP923. The 12" is primarily navigation, radar etc and the 9" is primarily engine data, rear view camera etc. The plotters, radar and N2K are all networked, so everything is available to both plotters. At the lower helm i have two Android tablets, each has Garmin Active Captain installed and one connects wirelessly to each of the plotters on the flybridge. Everything works just fine.

The image in post #11 was taken from the tablet at the lower helm, which was mirroring the 9" plotter on the flybridge.

 

[lustyd]

Paul did you need to put terminators in for the ve.can?

 

[PaulRainbow]

Paul did you need to put terminators in for the ve.can?

No, just plugged into a Can port. The Can to N2K cable is treated as a spur/drop cable.

 

[lustyd]

Thanks, I think I may try this as it would be nice to get the data into the MFD as fields rather than an app.

I may need to look into how the ve.can works, I think I've assumed a few things that are wrong

 

[PaulRainbow]

Thanks, I think I may try this as it would be nice to get the data into the MFD as fields rather than an app.

I may need to look into how the ve.can works, I think I've assumed a few things that are wrong

Victron docs can be a minefield. There is much said about VE-Can and terminators, so one would assume they are always needed, but they are not. TheVE Can to N2k is one example where that's not the case.

If you connect more than one VEcan device together the tow devices at either end need to be terminated. It looks as though VEcan will treat a single device as a spur but multiple devices look to be daisy chained and then have to be terminated. Be interested to hear what you learn.

 

[lustyd]

I would assume that to do it correctly you'd want some kind of a T connector just like any other CAN, although good luck finding one with RJ45s. N2K will also work by just connecting but it's not correct and will fail as you scale it. I doubt it matters here unless you build out a CAN as well but I'll see what I can find just out of interest.
Either way very useful to know how the cable works and I'll be fitting one to try it out so thanks!

 

[PaulRainbow]

I would assume that to do it correctly you'd want some kind of a T connector just like any other CAN, although good luck finding one with RJ45s. N2K will also work by just connecting but it's not correct and will fail as you scale it. I doubt it matters here unless you build out a CAN as well but I'll see what I can find just out of interest.
Either way very useful to know how the cable works and I'll be fitting one to try it out so thanks!

No tees that i've seen. Each VE-can device has two ports and they daisy chain together, the device at each end then has a terminator. They must be internally connected as per "normal CAN to form the network. Something internally must recognise the VE-can to N2K connection and treat it as a spur.

 

[lustyd]

Right, altogether too much reading to get to this very simple conclusion but I have an answer all the same.
Nmea2000 is effectively a CAN network as I’m sure we all know, with some subtle changes like connectors. The reason we don’t need to terminate the CAN is that there isn’t one of you use NMEA2k. The docs don’t explicitly say it but the diagrams clearly show that instead of a terminated CAN, every Victron device needs a N2K drop cable. It’s either/or and you only get one backbone.
The two ports on the Victron devices are the tee connector, and plugging one side in electrically just makes it a drop connector (since they’re passive straight through between them).

Seems obvious now I say it. It makes sense too since Cerbo can then read N2K tank sensors so seems best to chose those if connecting the two systems to avoid having even more rj45 drop cables.

 

[PaulRainbow]

Right, altogether too much reading to get to this very simple conclusion but I have an answer all the same.
Nmea2000 is effectively a CAN network as I’m sure we all know, with some subtle changes like connectors. The reason we don’t need to terminate the CAN is that there isn’t one of you use NMEA2k. The docs don’t explicitly say it but the diagrams clearly show that instead of a terminated CAN, every Victron device needs a N2K drop cable. It’s either/or and you only get one backbone.
The two ports on the Victron devices are the tee connector, and plugging one side in electrically just makes it a drop connector (since they’re passive straight through between them).

Seems obvious now I say it. It makes sense too since Cerbo can then read N2K tank sensors so seems best to chose those if connecting the two systems to avoid having even more rj45 drop cables.

Unless i'm misunderstanding what you have typed, that's not entirely correct.

1) If you want to connect a single device to the N2K network a VE-Can to N2K cable can be used and will, as you say above (and i said earlier), be treated as a drop cable. Multiple VE-Can devices can be connected to the N2K network in this way.

2) On the other hand, VE-Can can be used to construct a VE-Can network. As i posted earlier, multiple VE-Can devices can be "daisy chained" together, with the two end devices (those with only a single connection) need to be terminated. If using this method i'm not sure how you make the N2K connection.

Ref tanks sensors, there are a few ways to connect these. N2K sensors can be connected to the N2K network and that data will be available on the VE0Can "network" as in 1) above. Or, analogue sensors can be connected to the tank inputs on a Cerbo and that data is available on the N2K network. I have my analogue water tank sensor connected to my Cerbo and i can read the data on my GX Touch70 or the N2K network.