Reading registers of FOX ESS S2500-G2 Inverter using RS485 Modbus RTU, gives timeout

[async]

Hi there.
I'm trying to read some registers (e.g. InvTemperature) of my FOX ESS S2500-G2 Inverter.

The setup is relatively simple:
1) 16-pins COM port of the S2500 is using pins 1 (A+), 2 (B-) and 6 (GND) (conform FOX S2500-G2 Use Manual)
2) Connected via CAT6 wiring pairs to a Waveshare USB to RS485 presented as COM3 on Windows 11
3) Using "mbpoll -a 1 -b 9600 -d 8 -s 1 -P none -m rtu -t 3 -r 28 -c 1 COM3"

Which returns this error:

Read input register failed: timed out

I've tried several different settings like slave ID 247, inter changing PIN1 and 2 and other register numbers. I even measured the voltage of the PINs to exclude wiring faults. Also using different tools like QModMaster gives exact same error.
I extracted the Register information from a Chinese FOX document that I received from FOX Support that I translated to English; so I'm not exactly sure if Input Register 29 of 28 is correct. However, I think I'd receive a return error other than "Timeout" when reading a wrong register?
Anyhow, I can't think of why or where this is going wrong or how to troubleshoot this further…
Anyone with some fresh ideas?

Background info: this is a test setup. Ultimately I want to use HomeAssistant to set an Export Limit register to prevent feed-in charges.

[Dave Foster]

Unless Fox have changed it (very recently), the S series does not support modbus inspection of the registers - it may be possible to see the data that is sent to the datalogger on the RS485 lines but that will not be a polled message, it will be a modbus status message transmitted every 90 seconds or so.

There were a couple of projects on github for the T series and from memory I thought the S series could be data harvested that way as well - see here https://github.com/assembly12/Foxess-T- ... -Assistant and here https://github.com/LucasTor/FoxESS-T-series

[async]

Oh, I see.
I'll ask FOX Support to verify this as they did not specifically mention it in a previous support ticket I raised on this matter.
Anyhow, thanks for your insightfull reaction!

[Dave Foster]

No problem, thanks - please let me know what you hear back from Fox support, at some point it seems logical that Fox will provide modbus access on the S & T series much like their bigger siblings