I want to read Dyness B4850 with a RS485 USB comms cable.

According to Dyness manual:

Pin 1 RS485-A

Pin 3 RS485-B

Have wiring sorted for other BMS running Pylontech, so USB to 485 working.

Found Dyness software online that sends out what looks like comms to read each register in a sequence.

No matter what BMS DIP settings I set, the BMS does not answer.

If anyone have a working coms setup I can learn from, please contact me. The information on the net is very limited.

Edited February 27Feb 27 by lcj

share me the software I can advice

Thanks for the reply. I don't know how to share the software. Upload limit of 3MB. I have the DIP switch setting that show the different Master Sequences #1 - #6. None of the DIP switch arrangements respond, so the BMS port could also be damaged.

https://dyness.com/Public/Uploads/uploadfile/files/20241023/B4850UserManualEN.pdf

I'm trying to figure out why my B4850 BMS isn't responding at all on RS485 — same USB-RS485 adapter works perfectly with my Pylontech setup. I've tested multiple DIP combos (e.g., #2+#3 ON for Growatt SPF RS485 mode at 9600/115200 baud), but still no reply to any read requests.

If you've got direct experience with reading registers from the B4850 via RS485 (protocol details, confirmed baud/slave ID, or a working sample frame/hex that elicits a response), any quick pointers would be appreciated — info online is very limited. Thanks!

I've also not been able to find information where an inverter to BMS setup works on a standard protocol.

On 2026/02/25 at 8:10 AM, lcj said:

Thanks for the reply. I don't know how to share the software. Upload limit of 3MB. I have the DIP switch setting that show the different Master Sequences #1 - #6. None of the DIP switch arrangements respond, so the BMS port could also be damaged.

https://dyness.com/Public/Uploads/uploadfile/files/20241023/B4850UserManualEN.pdf

I'm trying to figure out why my B4850 BMS isn't responding at all on RS485 — same USB-RS485 adapter works perfectly with my Pylontech setup. I've tested multiple DIP combos (e.g., #2+#3 ON for Growatt SPF RS485 mode at 9600/115200 baud), but still no reply to any read requests.

If you've got direct experience with reading registers from the B4850 via RS485 (protocol details, confirmed baud/slave ID, or a working sample frame/hex that elicits a response), any quick pointers would be appreciated — info online is very limited. Thanks!

I've also not been able to find information where an inverter to BMS setup works on a standard protocol.

Got something working after hours of trying. Dyness documentation for this BMS pin out is not the same as the technical manually claims. The software I tried using before also does not work.