FoxESS Community - Owners & Installers Forum

Hi
I have a Fox ESS H1-3.7-E-G2 inverter and am having issues retrieving its internal information via modbus.
In order to see what might be going wrong, I have connected a PC and USB to RS485 converter to the inverter's RS485 port and am using modpoll.
I seem to be able to get the registers controlling SOH, max currents etc. from the region starting at 41000 using either holding registers or input registers,
but a virtually identical command requesting registers showing voltages, currents, powers etc. starting at 11000 gives an error response - see below:

C:\>modpoll -a247 -r41001 -c10 -t4 -b9600 -1 -pnone COM4
modpoll 3.15 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2024 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC3
Slave configuration...: address = 247, start reference = 41001, count = 10
Communication.........: COM4, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, holding register table

-- Polling slave...
[41001]: 0
[41002]: 0
[41003]: 0
[41004]: 0
[41005]: 0
[41006]: 0
[41007]: 0
[41008]: 400
[41009]: 400
[41010]: 10

C:\>modpoll -a247 -r41001 -c10 -t3 -b9600 -1 -pnone COM4
modpoll 3.15 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2024 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 247, start reference = 41001, count = 10
Communication.........: COM4, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave...
[41001]: 0
[41002]: 0
[41003]: 0
[41004]: 0
[41005]: 0
[41006]: 0
[41007]: 0
[41008]: 400
[41009]: 400
[41010]: 10

C:\>modpoll -a247 -r11001 -c10 -t3 -b9600 -1 -pnone COM4
modpoll 3.15 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2024 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 247, start reference = 11001, count = 10
Communication.........: COM4, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave...
Illegal Data Address exception response!

C:\>modpoll -a247 -r11001 -c10 -t4 -b9600 -1 -pnone COM4
modpoll 3.15 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2024 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC3
Slave configuration...: address = 247, start reference = 11001, count = 10
Communication.........: COM4, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, holding register table

-- Polling slave...
Illegal Data Address exception response!

C:\>



The iPhone FoxCloud 2.0 app reports the following:
Version_master 1.14
Version_Slave 1.02
Version_ARM 1.17
If relevant, I have an ECS2900 cube comprising one master and two slaves attached. They say:
Version_BMS 1.011

Does anyone have any idea what might be causing this?

Kind regards
Mike Robins

I don't know if it will help you but all the working addresses are used in this project
https://github.com/nathanmarlor/foxess_modbus

Thanks for the quick reply.
I am not planning on using Home Assistant.
I garnered the modbus addresses from https://github.com/nathanmarlor/foxess_ ... -Documents, Fox.-.AIO.H1.modbus.-.2023.pdf, on which I guess nathan based his Home Assistant integration.
Kind Regards
Mike Robins

depending on firmware version of the inverter the modbus addresses changed in recent firmware.

Hi Will
Do you know if they are different in version(s)?
Or should I get the firmware updated to the latest?
If so, is this something I can do myself (reasonably confident electronics and software engineer) or should I get my installer to do so?

By the way, the numbers displayed by the FoxCloud 2.0 app don't seem to add up. Could this be related to the out of date firmware versions?

Kind regards
Mike Robins

Mike Robins wrote: Sat Mar 22, 2025 7:42 pm Hi Will
Do you know if they are different in version(s)?
Or should I get the firmware updated to the latest?
If so, is this something I can do myself (reasonably confident electronics and software engineer) or should I get my installer to do so?

By the way, the numbers displayed by the FoxCloud 2.0 app don't seem to add up. Could this be related to the out of date firmware versions?

Kind regards
Mike Robins

Yes the firmware changes the register maps quite dramatically - get yourself on the latest version of Master/Manager firmware, the versions you have posted are really old and so any work you do now may become obsolete when you are updated.

I shall get the installer to update the firmware. But I don't know how long that will take. I will update this topic when that is complete.
Mike