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thefu avatar image
thefu asked

Cerbo GX Mk2, issues connecting to RV-C on Newmar New Aire

I am at my wits end. That is why I am now here. Let me explain my set up and then where I have come to an impasse. I hope someone out there can help.

I have recently embarked on swapping out my 8 AGM on my 2021 Newmar New Aire for three 460ah LiPo4 batteries from Epoch. These batteries have a Victron-compatible Can-BMS port. The Newmar uses Silverleaf and a RV-C (via Xanbus) connected Xantrex 3012 Inverter.

The changeover went well and all the base systems are working fine.

First let me be clear - because this may or may not make a difference in your answers - I have the newest model of the Cerbo, the Mk2. I have updated the firmware to the latest (March 2024) version.

I installed the Cerbo and connected the batteries to it in the leftmost connector in the leftmost set of ports (VE.Can 2) and have installed the Victron terminator in the other connector. I configured what is labelled in the menus as "BMS Port" in the software menus to be BMS. The information is coming across to the Cerbo as one would want. Packets are moving.

Then, I wanted to connect the Cerbo to the coaches RV-C network. I found out that my coach, and Xanbus implementation, of RV-C over RJ45 connections happens on different pins (4/5) than Victron (7/8). So I made a patch cable, tested it for continuity (even made two), and connected 4->7 and 5->8 as described in various Victron info pages. I removed the terminator on the Xantrek, connected the cable, and connected it into the left connector of the middle set of ports labelled Ve.Can 1. I then went to the software and for the selection labelled Ve.Can I changed the setting to RV-C. No data comes across, only a handful of packets come up on the Rx side and none on the Tx side.

I have swapped around the cables between Ve.Can 1 and Ve.Can 2 and as well the software configuration and in the middel Can ports, VE.Can 1, the BMS does not work at all, and on VE.Can 2 with the RV-C connection and software selection it does not run either.

What gives? I know this configuration should work. What am I doing wrong!?


cerbo gxBMSVE.Can
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6 Answers
thefu avatar image
thefu answered ·

Cabling pinout issue, bad cable crimp, foreign matter in one of the connectors (they face up) all contributed to this issue not being easily diagnosed. Chasing tail.

Victron sent me another unit - couldnt get it to work at first - found the bad crimp - then still could not get mine to work - found the plastic down inside the connector.

Grrr... Feel like an idiot in a way - but sometimes when multiple things are causing issues...

Now RV-C is operating and i can see tank levels on the Cerbo and the battery info on the coach.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

Thanks for the follow up explanation @TheFu - happy to hear it is resolved and things are working.


It’s remarkable how often these issues come down to the cables.

I wrote this guide for our VE.Bus a little while ago because I was constantly hearing about the same thing, custom cable crimp looks fine, EVEN TESTS FINE, and then is the cause of all sorts of unusual behaviour.

https://www.victronenergy.com/live/ve.bus:ve.bus_network_interference

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phil-garver avatar image
phil-garver answered ·
I am actually having the same issue, with same battery setup and MK2, but on a different system, a Tiffin Spyder RV-C. However, what you described is exactly the same issue I have. Following / will update if I find anything.

Question, you are able to see the Batteries ok, correct (I am, want to confirm you are).

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thefu avatar image thefu commented ·
Yes, the batteries communicate fine with the Cerbo - you can see the packet traffic and the data comes over. It's the RV-C side that does not. I am fairly certain I have the wiring correct with the 4->7 5->8 patch cable. Wondering if there might be some other firmware issue related to this in the Mk2.
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Justin Cook avatar image
Justin Cook answered ·

Are you sure your coach is actually running RV-C and not Xanbus? They're not the same, and I wouldn't expect a Cerbo to be able to communicate with Xanbus.

Xantrex does make particular inverter/chargers for RV-C rather than Xanbus, like the Freedom SW-RVC series, but if the system in the coach is Xanbus instead of RV-C then that'll be the issue.

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phil-garver avatar image phil-garver commented ·
For my setup, yes, it is RV-C.
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thefu avatar image thefu commented ·

Yes it is RV-C. Since you are responding here, and an expert, I can only assume you have not done an install on the Newmar before so that is why you might be unfamiliar. Sorry for any confusion on my part.

Also, the menus in the firmware (3.3) still reference a "BMS" port but one does not exist any longer. It is incredibly confusing and dealers are not up to date on this new model - some did not even know it existed or thought there was no material difference with the Mk2.

As an expert, how would you determine how to wire up the Xanbus 3012 clearly connected and communicating with RV-C as it is listed on the Silverleaf device list, but will not comm correctly according to the info I posted above. Suggested troubleshooting steps you would take?

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thefu avatar image
thefu answered ·

Also, from what I can tell, no updated manual has been posted yet for the Mk2 model. And, as I said, the firmware menus do not align up with the labels on the ports any longer as well.

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phil-garver avatar image phil-garver commented ·
One thing I have noticed is the tap point for my RV-C only has Blue and White wires (CAN Hi and Low). Not sure if this is causing an issue or not. There was an RV-C (Go-Power) solar controller in this tap point that was working, so not sure if the Cerbo needs the ground reference and that is causing the issue. Will look to update the tap and try.
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thefu avatar image thefu phil-garver commented ·
Ground is really not necessary in this configuration - at least according to the engineer at the Victron dealer I spoke to. Most 2-wire comm systems like CanBus are fine with just the two wires.
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jfbauerjr avatar image jfbauerjr commented ·
Can I get some help from you, just installed a victron solar system in my new aire. The tm-102 not working, I'm convinced it's that xanbus interface plug from the xantrex 3000 watt inverter we removed. I'm trying to figure out how to get it hooked up to my rv-c network so my silverleaf works again. Thanks
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thefu avatar image
thefu answered ·

So I just got off the phone with an engineer at Solar Energy Systems to go over all that I have done and see what he thinks. He did not have any experience with the Mk2 and RV-C yet but said that to him it sounded like (given all the work and testing I have done) that it could be something with the firmware in the unit. I also find it strange that in the firmware menu, the settings for the the two ports still have them labelled the old way. He suggested trying an original Cerbo to see. I don't have one handy and really dont want to order one just to test this theory. I am going to go back out and make a new patch cable, test it for continuity, and see what happens. I guess it is also possible that the Ve.Can1 port is bad, but if that were the case, why would it not work on Ve.Can2 when configured as RV-C when the batteries work fine on Ve.Can2 when its configured as BMS.

It would be great if someone from Victron sees this and at least brings it to the engineers and gives it a look - and if alls well, tell me I am crazy. I am fine with that :)

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mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi all, sorry to hear about the confusion, but glad to hear you were able to make it work in the end. We've added further details to our GX product range page, all the details are in foot note 25:

https://www.victronenergy.com/live/venus-os:start#notes

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