question

@mattyroo , Maybe draw it out. But a few things.

1) if you remove the fuse in the VE CAN to NMEA2k adapter cable, then no power can get from the N2K network to the VE.Can segment or visa versa.

2) depending on the bridge you use, some do come with the ability to filter and control traffic flowing through. The ones I have used do not have nice graphical interfaces and building rules is very challenging.

3) N2K, VE.Can and J1939 are all CAN, it is just message structures on that CAN network that vary. They all use the same underlying ISO based messages for device address negotiation and other low level CAN requirements. That means the N2K messages, J1939 messages and VE.Can messages will sit happily on a single CAN network

4) The Cerbo ports not being isolated is not necessarily an issue. the CAN specification does not state it must be, N2K spec requires it.

With all that said, I have a single backbone made up of VE.Can (RJ45 connectors), N2K micro connectors and Raymarine STng connectors. That network is carrying J1939 engine data, N2K, Victron VREG, some RV-C messages, oh and some legacy 11 bit messages. All without any issues. I have 3 different power inject points, and at selected points in the network I have broken the + / - feed between parts of the backbone. This allows me to have the VE.Can Victron devices permanently powered (although I do not believe any Victron devices takes power from the CAN network). A few N2K devices permanently powered. The STng segment powered when I have my navigation kit on, and finally a segment with my engine gateway on, which is only powered when the engine ignition is on.

I have a total cable length of maybe 30m, total device count of maybe 20 devices when everything is on and a network load of between 5 and 45% depending on what kit is powered and how many AIS targets are being detected.

I know what I have done breaks N2K and Raymarine design specifications and documentation. However, when you read about CAN networks, breaking the power is a valid way of segmenting and controlling the network. You just need to ensure that there is only one active power feed for each part and that there are only 2 terminators.

Hope that helps.

@Bathnm, thanks for your detailed reply.

I do have very detailed drawings, but I'm in two minds on whether to share them, as they have a significant amount of IP in them... Therefore I knocked up a simple overview schematic.

I think I will ultimately have 4 or 5 CAN networks, depending on how the final topography looks.

The existing Raymarine Seatalk network, which will be bridged to the new CZone NMEA network, via a bridge that isolates the power of the 2.

The aforementioned CZone network (this is new and the nexus of the upgrades that are currently underway), which is used for control and monitoring of the boat electrical equipment - this will also be connected to the Mastervolt Masterbus CANBUS network, via a CZone MB bridge, this is the only interface the MB network will have.

What I call the "BMS network", this has the Orion JR2 BMS and an OBD device on it currently, and is not integrated. I need to integrate it, so that messages can be passed from this to the CZone, Masterbus and Victron networks, to control chargers on all of these networks, primarily by sending the Li-Ion battery bank SoC from the BMS to all devices, to either suspend charge or drive the device to float. The Orion BMS and the Victron products have a paper detailing how to do this, using Victron DVCC. This will be a DIY network, using terminal blocks and off the shelf $1 resistors, other than the resistor that is pre-installed in the BMS.

The Yacht Devices YDNB-07 bridge I anticipate using to send the data from the Orion BMS to the CZone network, which, being integrated with the MV MB network, I can use the SoC to control the Alpha Pro alternator regulators.

Finally, I have the Victron network(s)...

Unfortunately, the boat has a couple of VE Direct charge controllers already installed, and to limit cost, we're going to use these. The VE Direct devices (2x MPPT and 1x Smart Shunt) will connect to to the Cerbo via VE Direct.

I'm going to install 2 x new VE-CAN MPPT controllers for the large new solar array that is being installed on the arch. These will be connected together on the CANBUS, with one dropping into the Seatalk network, and the other connected to the Cerbo.

The already installed Multiplus Inverter will connect to the Cerbo via VE BUS

The Cerbo I am going to then drop to the BMS network. I think, as the VE CAN ports are not isolated, I can use this cable as the powering device for the BMS network. I think I will use a heavy Ancor NMEA backbone cable to do this, rather than a standard LAN cable, as it could be about a 12m run, and I don't want voltage drop issues. Thoughts?

Where I can potentially see an issue, is that the Victron networks will effectively be connected to the other networks twice, by connecting directly to the Seatalk network, and by connecting to the BMS network, which will connect to the CZone network, via the Yacht Devices Bridge, which is then connected to the Seatalk network via the CZone bridge.

Whether I can limit the Victron messages being duplicated remains to be seen. Ideally I want them on the CZone network, but only via the least messy route, which I figure might be via the BMS network and the YD bridge.

Alternatively,, what may be an even more messy, but in some ways cleaner process would be to have the Victron network also connect directly to the CZone network.

Any advice, feedback, thoughts etc. would be greatly appreciated.

CANBUS.pdf