question

vick-da-aerbus avatar image
vick-da-aerbus asked

Need one more CAN bus port for NMEA and SEELEVEL tank monitoring

Setup.

I have a Multiplus II connected to a Lynx distributor. On the distributor are three MPPTs and soon, one Orion DC-DC charger. I have a 712 battery monitor connected to the shunt. The MPPTs are daisy chained to the Cerbo GX CAN. The Multiplus is connected to the Cerbo via VE Bus. I plan on connecting a resistance LP tank monitor to tank 1 input. Finally, I am installing a 709-N2K to monitor the water and waste tanks.

Problem.

The CAN Bus is terminated on both ends. However, that leaves no space for the N2K. Is there a way to make a hub for extra CAN units? Is a VE.direct connection between the MPPTs and the Cerbo the work-around to daisy chaining the MPPTs on the CAN network?

VE.DirectVE.CanNMEA 2000 - N2K
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3 Answers
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

@Vick da Aerbus

VE.Can/N2K are virtually the same, thus it doesn't matter where you terminate the network, ie. a VE.Can terminator at the last MPPT and another terminator at the N2K end.

You can use a VE.Can to NMEA 2000 micro-C male cable as a drop cable.

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wudwork avatar image
wudwork answered ·

I have that, and more, all working great. 1) I put in THIS usb hub and connected each of my 3 MPPT's and USB-Bluetooth to that hub. I then connected that hub to Cerbo (using yet another of the expensive cables) so on Cerbo there is a VEdirect connection that ties in all MPPT's, as well as my bluetooth adapter. In effect, all my VEdirect stuff is in parallel; I chose NOT to daisychain. You will need THESE expensive USB-VeDirect cables; one for each MPPT and another to Cerbo. 2) Across the top of Cerbo, I use (2) VeDirect ports. Leftmost goes to BVM-712, next is the connection to USB port. The Ve.Can has 2 ports, left is Seelevel, right is terminator. Rightmost connections: one is regular Cat5 computer cable to Multiplus, other is regular Cat5 to my network hub. Note: with the network hub, I can access my Cerbo from any laptop/ipad/desktop/phone etc. via the IP address of Cerbo.


HTH, Tom

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Kevin Windrem avatar image
Kevin Windrem answered ·

As Stephanie suggested, connecting your MPPTs and the SeeLevel to the same bus should work fine. CANbus is a parallel connection, terminated at the far ends of the bus. For SeeLevel, you need to adapt an RJ-45 to the little 4-pin connector. If the termination ends up with SeeLevel, fitting a termination resistor into that connector can be done but it's best handled in the wiring before that connector.

Using the cable Stephanie referenced gets you to a standard NEMA 2000 connector which you'd still need to adapt to the SeeLevel connector, and find a place for the termination resistor. You can use NEMA 2000 taps, terminators, etc to make the necessary connections:

https://www.amazon.com/Garmin-010-11078-00-NMEA-2000-T-connector/dp/B0017VTAL6?th=1

https://www.amazon.com/Female-Terminators-Terminating-Lowrance-Networks/dp/B086VCRBXP

If you prefer, you can add a USB CANbus adapter to your system to sepratete the SeeLevel N2K on it's own bus. Any adapter that uses GS USB should work fine. Note that some CANbus adapters use slcan and those are known to be unreliable and won't work plug-and-play.

The built-in and GS USB CANbus adapters should work plug-and-play but there could be issues with ports moving around as they are numbered in order of discovery.

VeCanSetup can be used to activate an slcan interface or to allow naming of all CANbus ports and avoiding discovery order issues.

https://github.com/kwindrem/VeCanSetup

2 comments
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@Kevin Windrem

The 709-N2K does not have an N2K (N2K standard micro M12) connector? I did not know that. The name says something else, that's why I recommended the Victron cable.

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Kevin Windrem avatar image Kevin Windrem Stefanie (Victron Energy Staff) ♦♦ commented ·

Sadly, no. I did find this article describing how to make a cable including the 3M connector number:

https://www.vanlifeoutfitters.com/using-seelevel-tank-monitoring-with-a-victron-energy-cerbo-gx/

They show the termination resistor inserted with the wire. I did this initially but my connections were intermittent. So I added the resistor between the CAN Low and CAN High wires slightly away from the connector.

I also did not connect the VOLTAGE + wire. You do need the ground wire if the CANbus adapter (including the Cerbo internal ones) is isolated.

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Related Resources

Additional resources still need to be added for this topic

VE.Direct protocol FAQ