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Michael.Samer avatar image

VE.Bus termination

Hi at Victron

I'm wondering why the VE.Bus (e.g. CCGX to Mulit-II) is not terminated any longer (while it was in the earlier implentations. While using EIA-485 it should be terminated (e.g. ISBN 978-3-8348-0425-9 or https://en.wikibooks.org/wiki/Serial_Programming/RS-485#Termination) on both ends of the chain preferable active (on longer connections) or passive (very similar to CAN). As most specs it will work even when it is not connected as long as the load is low and the cables short so reflections on the two ends are not excessive.

But why did you stop using (passive I guess) Terminators?

Cheers

Michael

VE.Bus
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4 Answers
Michael.Samer avatar image

Hi M.Lange
I was informed by my VE Partner that it was once terminated. As mentioned the EIA calls for it, so I wondered why it was not planned in the design phase. As mentioned before maybe the VE.Bus will not reach lenght/load or Speed which causes data corruption without termination
Cheers
Michael

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Michael.Samer avatar image

Hi mvader,

I'm more in a reason question than a technical one. I'm using the ProfiBus on a professional basis and as it's using EIA-485 as well I wondered. No termination even on short bus lenght (10m) would be treated as bad design in my (automotive) branch. Maybe you are not using the VE.Bus in such long distances so data corruption (reflection & load) is not imanent to cause a problem. Max. 9 Multis and one CCGX doesn't sound like 20m over all. Terminating all devices would cause unreasonable dampening of the signal which causes more problems than it would solve.

CAN (as well intensly used by me) explicitly calls for termination. Btw. CAN possibility was one of the reasons for me to go for Victron (even when I don't use any in my CCGX).

Cheers

Michael

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Hi Michael, thank you for the input. Although I dont know the details, I do know that considerable effort went into that, and I have full confidence in the developer that is responsible for this.

Sorry that I can’t give you the details but I don’t want to bother R&D for it.

You’ll have to trust us on it too. ;o)

Best regards,

Matthijs

mvader (Victron Energy) avatar image

Hi, I can’t remember ever using external terminators on VE.Bus. And I’m sorry but I dont know why we don’t. Perhaps we have a terminator on each board.

We do for VE.Can, perhaps that is where you’ve seen external ones.

Best regards, Matthijs

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Matthias Lange - DE avatar image

As long as I use Victron (more than 10 years) there was never a termination required for VE.Bus.

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