Thank you for your answer. If I understood correctly for the modbusRTU solution I have to use the knx-gateway and a modbusTCP/RTU converter like USR-W610, while for the modbusTCP I don’t need extra hardware (but have to use the NEA in AP mode with all the consequences it has). Is it right?
Thx and Ciao
Hi @franzer73,
The KNX gateway is not needed at all. The idea is to emulate the operation of the KNX gateway that works on one side with the ModbusRTU protocol (server) and on the other side with the KNX. We do not need the KNX protocol.
What I did is (only) to use an ESP32 and an XY-017 to emulate the ModbusRTU server of the KNX gateway. With this, the Nea Smart Base writes the data to the ESP32. By adding MQTT to the ESP32 I publish the data every so often and collect it in NodeRed. That’s all.
If I am not mistaken, what @vcalzolari64 is doing is using a device that already has the dual Modbus system. From what I read, he wants to do the data polling directly in HA.
I would be glad to share the code via email. Maybe the best thing would be to post it on GitHub but I have never done it and I do not have time to prepare the documentation, etc … But if someone is encouraged to do it, for me, no problem…
Adeu!
Hi @vcalzolari64 and @pistunut ,
my new house is almost ready and I will have 8 thermostats I’d really like to integrate with Home assistant.
I can help (when the house will be ready) for the hardware part, in the meantime I can support you in the development part, documentation and Github part (I’m a full time software engineer).
Please keep me posted
Hi @zelphir ,
Perfect, your help will be great! If you give me an email I will start passing you what we have done so far.
Salut!
Hey great to hear back from you. Please send me an email to [email protected] (just created an hide my email to mask my real email). If you and @vcalzolari64 send me your email addresses I can add you to the GitHub repo
Hello everyone! I too have a nea smart system with 7 thermostats and I’d like to integrate it into a home assistant for total control with the photovoltaic system.
I hope it’s not too difficult because I’m not very experienced… 
A thousand thanks!
Hello, I’m doing a HA system in a new house for a friend and he’s using a rehau nea smart 2. Can you share the project with me? @pistunut @vcalzolari64
[email protected]
Thank you!
Hey all,
I’ll be interested in participating in the creation of the integration too, I have a 3 zone system with 8 thermostats.
I’m not an expert but I just finished integrating my Helty HRV/CMV units with good results: GitHub - MatteoManzoni/helty-cmv-integration-ha: Helty CMV (Forced Ventilation with Heat Exchanger) HomeAssistant Integration
My email is: [email protected]
Best,
Matteo
Hello everyone! Yesterday my NEA Smart 2.0 system was set up and I’m using geofencing to change home/away modes…
I changed my mind and now this makes me a bit uncomfortable after reading about the security issues: how can I try to use HA and the apple
Home app?
Thank you!
Hello,
From what I understood, you have already managed to do what I have been trying to achieve for the last 3 months 
I have the NEA SMART 2.0 Base connected via RS-485 to my computer right now. What I don’t understand is 1) how to send data to the unit 2) how do I know what register to write to do certain things, the KNX documentation sucks.
Could you please help me out a bit?
Thanks in advance 
I have now my system installed, I would like to know your setup. Can you please share it, PM? Thanks!
Hi at all. I have also Rehau nea smart 2.0 and two raspis. Actually I use Homebridge, Grafana and Iobroker, but to use Rehau in HomeKit I would install Home Assistant. Have you any Instruction how I can import Nea smart 2.0 to Home Assistant? I can’t find any except the instruction für knx. But I have no Knx. I like to use it only for HomeKit. Thx at all. Pls link me the instruction. and sorry for my bad English
Hey @pistunut @vcalzolari64 @zelphir,
Does anyone know the state of the project and how to get involved?
I would love to help but I’m also willing to start a new integration on my own with whomever else will be willing to help me
Please, please, keep the community posted and involved 
,
Matteo
Hey all,
As promised I’m working on an integration of my own, expected to be released during the weekend.
My integration is interfacing with a custom add-on exposing a shim server between the Rehau NeaSmart 2.0 registers Sysbus (ModbusRTU) and a set of rest APIs, this add-on supports both Modbus RTU to Modbus TCP gateways (they need to support “client” aka Modbus Slave mode) or local RS-485 to usb adapters. In my specific case I went with the first option creating a gateway with an Arduino board (now substituted with something fitting on a DIN rail and that supports PoE) but you can do the same with cheap-ish off-the-shelf devices like this one or ESP.
The add-on is here, documentation on how to install and configure it enclosed.
See you all in a few days when the integration will be ready (will be published through HACS)
Best,
Matteo
Hey all,
Me again, this is the first iteration of the integration.
Happy to receive any kind of feedback on it
Best,
Matteo
Congrats for your work.
But I think that for it to have sucess with others users you should better document the Hardware part.
From the Modbus connection from the system, to the available options for Modbus harware, and to configure it.
Hey @zbuh,
You are definitely right, what I focused on with this first iteration is time to market as myself with many others were waiting for some development that was never open-sourced.
I’ll try to add some more details in my documentation (and screenshots) about how to configure the specific model of modbus tcp gw I’m using, as for schematics/configurations on how to create a gateway with arduino/ESP or how to use the add-on with a homeassistant-attached serial to usb adapter I’m more than happy to accept contributions as, full-disclosure, it’s an effort I cannot justify right now
Very nice Job!!! I am so happy, but I need more instructions für the Serial to USB and Hardware etc. I can program Homeassistant but not more ^^ Can you make a tutorial or a Youtube Video? It will be so nice! I can barely wait for it. Thank you so much