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H3 RS485/modbus USB Adapter over LAN

Posted: Mon Mar 31, 2025 8:21 am
by dripphone
Hi,

I would like to use a rs485/usb adapter connected to the comms port pins 1+2 of H3 to access modbus from HA.

But the HA Foxess modbus Integration seems to require only local USB devices to configure. My USB Adapter is connected on another linux host in the LAN.
Any idea how I can use it remotely from HA? Like ser2net or similar?

Thx

Re: H3 RS485/modbus USB Adapter over LAN

Posted: Mon Mar 31, 2025 12:20 pm
by dripphone
UPDATE:
sorry, I just realized there are indeed LAN options to configure, like "Direct LAN connection" or "Ethernet to Modbus/RS485 adapter".
But somehow none of them work for me (using ser2net on the remote host).

I get:
Modbus Error: [Input/Output] Modbus Error: [Invalid Message] No response received, expected at least 8 bytes (0 received)

I assume I have some cabling issue. I need to check further, and will update here...

Re: H3 RS485/modbus USB Adapter over LAN

Posted: Tue Apr 01, 2025 7:24 pm
by dripphone
UPDATE2:
Finally it works. ser2net was NOT working.

I used "mbusd" on the remote Linux host to relay it as "modbus TCP".
Now the nathanmarlor/foxess_modbus integration detects it properly.