question

lennycb avatar image
lennycb asked

RPI4 RS485

Hi, everyone. Me again with my "old problem".


I had already described the problem, but unfortunately the answers did not lead to a solution.

Therefore, for the sake of clarity, new.


I've been trying for a long time and can't find a solution.


Original setup:

1x RPI4 with Venus OS in the latest version

1x MP 12/1600/70 (connection via MK3)

1x ET112 (connection via self-made cable FTDI RS485)

1x shunt (connection via self-made cable CH340)

1x solar controller (connection via self-made cable CH340)


everything was fine until then and worked perfectly even after a restart.


Now a LiFePo4 with JBD BMS was added.

Here I had built the connection again with an adapter FTDI RS485.


From here it got weird. After restarts, the devices were found or not. Conicidence.


After all this got on my nerves, I exchanged all the cables for the original Victron ones.

For 120€ for 4 cables you should be able to expect a steady function.


But unfortunately not. The RS485 devices do not work.


now my questions:

What else can I do now?

Can I test the ET112 to see if it is sending correctly (RX/TX)?

Does anyone have the JBD-BMS with an org. Adapter run from PI?

Venus OSrs485
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pau1phi11ips avatar image pau1phi11ips commented ·

The ET112 should be flashing green and orange on the left LED if it's communicating with something.

By the way, this may or may not be related to the problem. I was using this driver to get my Daly BMS data in Venus (via the Daly RS485 USB cable). This was working wonderfully until I I added a ET112 (via RS485) to the system. I could no longer get either to reliably work at the same time. I've just sacked the BMS data off now as the ET112 is more important to me.

https://github.com/Louisvdw/dbus-serialbattery/issues/77

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lennycb avatar image lennycb pau1phi11ips commented ·

I've tested a lot here.

My last attempt at a solution was to change the ModbusID from ET112 to 2, because the BMS probably claimed 1.

Up to firmware 2.73 it runs on my PI4. After an update to 2.80 or higher, the BMS is no longer found.

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2 Answers
Peter Buijs - NL avatar image
Peter Buijs - NL answered ·

What about termination RS485

https://e2e.ti.com/blogs_/b/analogwire/posts/rs-485-basics-when-termination-is-necessary-and-how-to-do-it-properly

https://community.victronenergy.com/questions/2768/problems-with-rs485-adapter-to-connect-with-et340.html


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lennycb avatar image lennycb commented ·

I did not install a separate resistor. Was also of the opinion that this is already installed in the adapter itself.

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buddhafragt avatar image buddhafragt lennycb commented ·

Hi, this post is already 1 year old, but I have the same problem. I try 5 different RS485 adapters right now (including the original Victron) but no success. I have also tried a TCP adapter Elfin-EW11A and this working without problems.

Is there a solution for this problem now?

Victron is suspiciously silent and does not comment on the problem.


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Mike Dorsett avatar image
Mike Dorsett answered ·

Part of the problem may lie in the ID that the USB/RS485 adapter uses to identify to the operating system. Victron devices like the USB/VE direct and the USB/Mk3 have unique ID's that the operating system can use to track what's on which port. Finding out this data can be a bit tedious. If you have 2 RS485 adapters with the same OS id, then the os can get confused as to what is on which one. Obviously data intended for the ET112 will not communicate with the BMS. i did once come across an FTDI data sheet with instructions as to how to program this ID, but never got into the detail. I ended up using a python routine to determine the device on the end of each USB device link and using that data to get the correct allocation in my own code.

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Related Resources

Victron Venus OS Open Source intro page

Venus OS GitHub (please do not post to this)

Additional resources still need to be added for this topic