FoxESS Community - Owners & Installers Forum

Hi all,

I’ve installed the foxess_modbus_EVO integration by Adam Newberry, but I’m seeing some strange behaviour when trying to change the inverter’s work mode.

Whenever I try to select Force Charge or Force Discharge, I get this error:

"Failed to perform the action select/select_option. Unknown error."

I’m also seeing incorrect mode changes. When I change the mode, the system initially accepts it, but then it automatically switches to a different mode. For example, if I’m in Peak Shaving and select Self Use, it changes to Feed In First instead. And if I then switch it to Back-up, the mode ends up showing as Unknown.

Has anyone come across this before? Any idea what’s causing it or how to fix it?

Thanks!

Brian

First check that there are no schedules set or enabled in the inverter via www.foxesscloud.com/v2 - delete any that are there.
It is also possible that some of the EVO's modbus registers are different to those used in that integration.

IIRC force charge/discharge via modbus may not be available on some firmware versions

I have checked there are no scheduled or enabled via www.foxesscloud.com/v2.

nrb501 wrote: ↑Fri Mar 27, 2026 8:35 am First check that there are no schedules set or enabled in the inverter via www.foxesscloud.com/v2 - delete any that are there.
It is also possible that some of the EVO's modbus registers are different to those used in that integration.

IIRC force charge/discharge via modbus may not be available on some firmware versions

I'm having the same experience, and looking at the code, version 2 some of the registers are incorrect. Despite correcting this I'm still not able to get the work mode to stick. Not sure why but I'm trying to troubleshoot

Hi all,

I’ve finally managed to get the mode setting working on the EVO through Home Assistant using modbus. I’ve been in contact with Fox ESS support, and after they updated my firmware, everything is now working correctly. I deleted the mode schedule on my phone app.

I have asked Fox support how I can set the force charge and discharge using modbus. Hopefully they will get back to me shortly. They have been very helpful so far.

The firmware versions I’m currently running are:

INV_Master: 1.15
INV_Slave: 1.00
INV_Manager: 0.30
AFCI: 0.37
Software: 2.09
BAT_BCU: 1.004

Would be interested in your results

I currently have another issue

If I set schedule to force charge it does nothing
If I set “remaining time mode” in the schedule to force charge out side the schedules time it force charges.

If I disable the schedule, not delete it, it also starts to force charges all feels back to front.

Fox tested it said it worked ok for them
I tried it after their email and it worked.
Hours later I tried again and it didn’t work.

UPDATE 11/5/26

My ISO app auto updated today
It’s now version 2.2.11

What’s new….
• Add relevant business functions for heat pumps;
• Optimization of quick setting function;
• Add one-click detection for battery faults;
• Optimize the password reset function.

Well unless it’s a coincidence my issue is now resolved with Mode Schedule
Hope yours is too

Yes I've just tested mine and force charge and discharge work now

Now hopefully my automations will work!

Are you IOS?

SoFather wrote: ↑Mon May 11, 2026 9:21 amAre you IOS?

Sorry I don't know what that is. I did however just get a fox cloud app update

IOS = Apple Phone
Android = well Android Phone lol

Oh right sorry, yes I have an android phone.

MattyS wrote: ↑Mon May 11, 2026 9:07 am Yes I've just tested mine and force charge and discharge work now

Now hopefully my automations will work!

However, self use and feed in no longer work.

I just got another update lol
2.2.12 now

I've been doing some digging and some testing too, and what I've personally found is that to write to the work mode on theEvo, you use a 0 based system ( 0=self use, 1=feed in, 2= back up) but when the modes are read from the inverter, it uses a 1 based system where all write values+1.

I've confirmed this via setting "feed in" via modbus, it sticks and switches correctly, but then when the value is read by modbus, it shows "Back up", which is number 3 on the 1 based system.

MattyS wrote: ↑Wed May 13, 2026 9:20 am I've been doing some digging and some testing too, and what I've personally found is that to write to the work mode on theEvo, you use a 0 based system ( 0=self use, 1=feed in, 2= back up) but when the modes are read from the inverter, it uses a 1 based system where all write values+1.

I've confirmed this via setting "feed in" via modbus, it sticks and switches correctly, but then when the value is read by modbus, it shows "Back up", which is number 3 on the 1 based system.

Hi MattyS,

Which register are you writing to? I use 49203 which works with the 1 based system. Are you also on the same firmware versions which I posted last week? I couldn’t get the modes to work until my firmware was updated.

I am using Adam Newberry’s integration, are you using the same?

I am interested in how you are setting the forced charge and forced discharge. Can you share it with us.

Brian

BOD wrote: ↑Wed May 13, 2026 4:29 pm

MattyS wrote: ↑Wed May 13, 2026 9:20 am I've been doing some digging and some testing too, and what I've personally found is that to write to the work mode on theEvo, you use a 0 based system ( 0=self use, 1=feed in, 2= back up) but when the modes are read from the inverter, it uses a 1 based system where all write values+1.

I've confirmed this via setting "feed in" via modbus, it sticks and switches correctly, but then when the value is read by modbus, it shows "Back up", which is number 3 on the 1 based system.

Hi MattyS,

Which register are you writing to? I use 49203 which works with the 1 based system. Are you also on the same firmware versions which I posted last week? I couldn’t get the modes to work until my firmware was updated.

I am using Adam Newberry’s integration, are you using the same?

I am interested in how you are setting the forced charge and forced discharge. Can you share it with us.

Brian

I am using Adams integration with a couple of test tweaks, yes.

See, if I use the 1 based system on register 49203 for writing to my inverter, it fails and reverts to the mode it was already on. Switching to the 0 based has enabled it to work. I've added the Evo to an appropriate inverter following that pattern in the entity description file, but I'm going to test a better fix.

I haven't yet tested the force settings. It's on the list though.