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Help connecting H3-15.0-SMART to MODBUS

Posted: Thu Mar 26, 2026 9:24 am
by thommo17
Hi everyone,

I just got my Waveshare RS485 TO ETH (B) and have it powered with POE and got the settings as per this guide
https://github.com/nathanmarlor/foxess_ ... TH-%28B%29
Screenshot 2026-03-26 185401.png
I'm getting this error when trying to connect the HA plugin
Screenshot 2026-03-26 185343.png
Error connecting to your adapter or inverter. Ensure the adapter is properly configured and is correctly wired to your inverter (see the setup link above), then try again. Details: Modbus Error: [Input/Output] Modbus Error: [Invalid Message] No response received, expected at least 8 bytes (0 received)

I can see in VirCom that when I try and connect it will send and receive packets but I just get that error each time.
Screenshot 2026-03-26 185329.png
I feel like it is how I have the inverter side wired up.

I have an ethernet cable plugged into the meter port and wire 1 and 2 into the corresponding port on the adapter with A to A and B to B. I can see the manual for the inverter says the meter port give out meter 485A and 485B on this port.
Screenshot 2026-03-26 191950.png
Or do I have to use the big COM port plug?

Thanks for any help!

Re: Help connecting H3-15.0-SMART to MODBUS

Posted: Thu Mar 26, 2026 5:13 pm
by Dave Foster
Yes you should be in the big COM port, the meters use a different 485 protocol.

The COM port has pins labelled EMS485 A & B (sometimes just labelled 485A/B) - they are the ones to connect to.