question

sylk avatar image
sylk asked

Ve.can termination, but where?

Hello all,

I made below a scribbled plan to my system.

The 2 right mppt's on ve.direct and the pylontech batteries with their bms connected om ve.can were working for some time without problems. Pylontech bms connected to ve.can was installed without any terminators, either on gx or the battery and it worked fine.

However, needs arrised for a 3'rd mppt. I can t connect it on ve.direct, since i have only 2 ports. Simple connection on the free ve.can port did nothing, so i figured out i need terminators. But where should i put them? On mppt only, or on mppt and on the pylontech battery? Wich one, first, or last?

Thank you!

img-20230520-084605.jpg

MPPT ControllersVenus GX - VGXPylontechVE.Can
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5 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi all,

The Venus GX has two independent CANbus interfaces. One with the RJ45 sockets, which can be set as either VE.Can or BMS-Can.

The other are terminal connections and cannot be set to VE.Can, only to BMS-Can. So it is that one that you should connect your Pylontech batteries too.


Both CAN interfaces specify using a terminator at each end of the bus. In the case of the Venus GX, as the BMS-Can terminals are not RJ45 is not so easy.

One terminator should be used on the Pylontech end, that is straight forward.

It IS possible to use a specific resistor (that is what is inside the supplied RJ45 terminator) to the Venus end. However given that the battery is the only thing on that bus, and presumably the cable is only a few meters long, and you can route it so that it is far away from any electrical interference (don't run it along side the power power cables), you should be able to work without it.

The terminator is there to absorb an electrical echo that can cause interference back on the line. The noisier the line, the more signals, and the longer the cable, the worse the effect and the more important the terminator is.

If you DO have issues with battery communications, then come back and we can look into what next.

This was all simplified with the Cerbo GX where both CANbus interfaces use the RJ45 sockets.

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ejrossouw avatar image
ejrossouw answered ·

The Pylontech string will require a one terminator on the Venus device. I propose you purchase a VE.direct to usb dongle to connect the 3rd MPPT to one of the usb ports. The VE.can MPPT cannot be on the same string as the batteries.

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dansonamission avatar image
dansonamission answered ·

The Pylontech batteries will be running at 500kbps where as ve.can devices, such as the Victron mppt run at 250kpbs. Your best option is the ve.direct to usb adapter as mentioned above.


https://www.victronenergy.com/accessories/ve-direct-to-usb-interface

2 comments
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hjohnson avatar image hjohnson commented ·
Cerbo GX's have two CAN ports, one of which (BMS-CAN) can operate at 500kbps. That should be able to communicate with the pylontech batteries, and then the MPPT can be on the VE.CAN interface. a USB->VE.Direct dongle would do no good, as that MPPT speaks CAN, not VE.Direct.
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nickdb avatar image nickdb ♦♦ hjohnson commented ·
He has a venus not cerbo and CAN mppts also are equipped with vedirect ports.
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sylk avatar image
sylk answered ·

Thanks a lot guys! You saved me from upgrading to a cerbo, i thought ve.direct to usb is only for connecting to pc.

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sylk avatar image sylk Matthias Lange - DE ♦ commented ·
Reading the manual told me that Venus gx has a non isolated bms-can port. Why can t that be used for pylontech, instead of occupying the ve.can port?
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4711austria avatar image
4711austria answered ·

if the Can sockets are not used on the Cerbo, should the terminator be placed on the Cerbo?

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pwfarnell avatar image pwfarnell commented ·
@4711Austria No, terminators are not required if the Can sockets are unused.
1 Like 1 ·