Page 1 of 1

Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 7:29 am
by albie999
Anybody have any idea what might be causing this?

For info ... swapped my router from Sky to Virgin Media Router, changed the SSID and password to same as on old router and all WiFi devices all connected fine.

The only thing that is not working is my modbus adapter to Home Assistant, although have not changed any settings on the modbus or Fox system and it is a ethernet cabled connection

I can connect to the modbus adapter (410s) via web browser, can ping it and can also get to the port (502). I just do not understand
modpoll.jpg

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:09 am
by Dave Foster
It depends which inverter you have, 11000 is the modbus input address for old H1's connected directly over LAN, I doubt there are any of those anymore, if you use an adaptor to connect it won't work (but will reply with illegal address).

For later generation inverters try this command

modpoll.exe -m tcp -p 502 -a 247 -t 4 -0 -1 -c 16 -r 31000 192.168.0.101

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:15 am
by albie999
Thanks Dave, have tried that command and seem to get a success
modpoll1.jpg

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:20 am
by Dave Foster
ok your inverter / adaptor and router connection is all working fine - in which case your IP address must have been changed since you installed the Foxess modbus integration

On HA go into Settings, Devices & Services, click the '>' on Foxess Modbus, then click the ''cog' icon, choose Network Settings and it will show what was originally selected, keep clicking submit until you get to the IP address and then make sure it is set to the current IP address and click submit - it should then be working.

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:26 am
by albie999
Thanks Dave, really do appreciate your help with this. I had already checked in HA .. and from what I can see .. all looked good
network1.jpg
network2.jpg
network3.jpg

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:37 am
by Dave Foster
hmm, that all looks good,
if you are not getting a connection is it possible the HA itself cannot directly address that IP address ? - you sometimes get that with routers that have wifi isolation or port forwarding.

In HA try adding the 'ping' integration in Devices & Services and the IP address of 192.168.0.101 and see if that returns a connection.

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:43 am
by albie999
Interesting, added another IP of another device .. and it was connecting .. but not to the modbus
ping4.jpg

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 9:56 am
by Dave Foster
Ok, looks like for some reason your router is blocking traffic between HA and the x.x.0.101 - i'll leave that with you to play :?

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 11:13 am
by albie999
OMG .. after literally troubleshooting everything .. and still not working .. I just thought ... hhhmmmm .... let me try a different network port on the router .... so moved my HA from the superfast Gb port .. to the standard port ... and it sprung into life
20260707_111017.jpg

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 11:26 am
by Dave Foster
That's a new one on me, every day's a school day !, glad you got it sorted :)

Re: Illegal Data Address Exception reponse from modbus adapter

Posted: Tue Jul 07, 2026 11:27 am
by albie999
Totally agree .. I did not think that the Gb port and the slower ports would be segregated .. ah well .. again Dave thanks for your help in daignosing ... on a positive point .. learnt more again on HA .. which is always a bonus