FoxESS Community - Owners & Installers Forum

Dear all,

I am running a H3 inverter + battery, using HOME ASSISTANT for monitoring via ModBus as it is described at Github.
Now I wonder, if it would be possible to "control" the inverter via modbus registers as well. In fact I plan to send the inverter to idle mode when there is no PV current and my batteries are empty (i.e. in winter overnight) to safe the extra power consumption of the interter.
Later when sun rise up again the inverter should come back to grid of course...
In principle this all can be done in homeassistant wiht an automation but I need the modbus register number. Currently I have the 31041 to read the inverter status - I just need the write register to control status.

Is there a chance to get that information?

Thanks a lot in advance!
Cheers!
Frank

This isn't that well documented and Fox are slowly changing the register map on later firmware versions for consistency.

However I believe on the H3 (and H1) that -

41013 is System Enable, where you write '0' to turn off, and '1' to enable

But you will obviously need to test it to be sure.

Dear Dave,

thanks for your answer!
From the modbus-list of H3 accessible to me I know that 41014 is "sys on/off". But, this switches off the whole electrical system - I just had "killed" my house with that register already in the past ...
Thus, I am not sure what "system enable" means exactly for 41013; probably it is the same.

From FoxESS there was a firm ware update last year that offers automatic switching the inverter to idle (not off) when the power consumption of the house falls below a certain value (e.g. 200W) at night. That works not good in practice since the consuption always alternates periodically (e.g. due to fridge) and at the end the inverter bounces from idle back to grid to idle all night long...
Anyway - that tells me that there must be the option to vary the status to Idle/grid/EPS/fault (regarding the status readings on 31041). Unfortunately I cannot find the register number

Kind regards,
Frank

I have 41014 recorded in the spec as EPS Frequency Select, and 41015 as EPS output Enable - nothing good would come of writing to either of those.
If you disable the system (41013) your power should stay on, but the inverter will no longer be providing any support - the equivalent of pressing and holding the check button on the inverter panel (second from the right) and selecting stop.

The H3 Pro follows the latest spec and does have an 'Idle State' but I am not sure whether this register mapping works with the H3 as it is very different but you are welcome to try it -

Idle State - 49229 (1 = enable, 0 = disable)

Idle loadpower threshold - 49230 (for H3 the range 100 - 200 watts)

Dear Dave,

thank you very much for the information! I am keen to test it when I am at home later - I´ll be back with a response tonight...

KR
Frank

Hello again Dave,

I have tested the 49229 - but unfortunately the inverter does not recognise this address. I'm afraid I need a firmware update first - that's planned for tomorrow...

Thanks again for the tip!

Frank

Dear Dave,

I just waiting for the firmware update by the support...meanwhile I tested a bit around...
Is it correct, that if I switch the inverter off ("sys off"") the EPS loads are switched off? (Grid loads staying alive) That is, of course, a vexation - since I have all my important circuits (as well as internet connection) at the EPS port.
If that "behavior" is correct, I cannot use the function "sys off" for my purpose...to optimize the power consumption during time periods without PV and/or battery.

KR
Frank

That's an interesting question and one that depends on how it has been wired but as you seem to have your important loads connected to it then I think the answer is sadly yes if the inverter is stopped your EPS will be off as well.

Hi Dave, this me again...

After upgrading to 2.04 Master and 1.8x Manager, I still cannot use the register 49229 (idle) (->unknown error). Is that adress correct for sure? If so, I would have to accept that I cannot solve my "problem" that easy via modbus, obviously...;-(

KR
Frank

Yes that is the address from the latest modbus spec and is definitely working on the H3_Pro - so it looks like the H3 doesn’t support this function via modbus

Thank you anyway for your information and support!

Bye, Frank