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This is a Home Assistant (HA) custom integration that enables communication between HA and specific Helios/Vallox ventilation systems via an RS485 interface.
The integration supports bi-directional communication for reading and writing system registers and coils, providing detailed control options.
It builds on the foundation of the SmartHomeNG-Helios plugin (see here), which has been in use since 2014 in my previous home automation setup with a Helios EC 300 Pro ventilation system. Other users have successfully connected the plugin to the following ventilation models:
- Helios: EC 200 Pro R/L, EC 300 Pro R/L, EC 500 Pro R/L
- Vallox: Vallo Plus 510 SE, Vallo Plus 350 SE, Vallox 910 SE, Vallox 090 SE, Vallox Digit SE, Vallox 130D (note: the 130D requires adjustments due to some different register numbers)
The following screenshot demonstrates how the data provided by this integration can be visualized in HA:
All Helios/Vallox ventilation systems consist of several components. Some are optional, but there is always at least the ventilation unit itself and one remote control:
The Pro (Helios) and SE (Vallox) models are equipped with an RS485 bus for communication between the mainboard of the ventilation unit and other system components, including the remote control(s).
A standard RS485 bus supports up to 32 devices connected in parallel. By adding a serial-to-LAN/WiFi adapter to the bus, we can enable software to act as a regular remote control. All that’s needed is to implement the (proprietary, non-standardized) protocol used by the ventilation components. This functionality is provided by this integration.
If you are not a electrical or electronics engineer or have no practical experience in this field, please ask someone who is qualified to do the wiring for you. Why?
Connecting the 24V internal supply to the wrong terminal is not a matter of trial and error. Incorrect wiring or accidental contact of +24V to the bus ports WILL harm the electronics of your ventilation.
Important: Always disconnect the device from main power before starting any wiring or connections. Make sure you pull the plug.
You will need:
- A RS485-to-LAN/WiFi adapter of your choice (a list of tested adapters and their setup will be included later),
- a short cable (20–30 cm) with at least two wires (five wires if the converter is powered by the bus).
There’s no need to be picky on the cable. In the predecessor of this integration, I successfully ran my adapter 24/7 for over 8 years, using two single NYM 1.5 mm² wires.
This project began in early 2014 on a Raspberry Pi Model B, which was connected to my Helios EC 300 Pro using a USB RS485 converter. The Raspberry Pi was running a parallel instance of my home automation system, dedicated solely to the ventilation.
After successfully implementing the first Python script, the idea soon arose to remove this parallel instance. Maintaining and synchronizing it with the main installation required considerable effort.
This led to the idea of connecting the ventilation system through a network-based converter, allowing direct control by the central home automation system.
In 2016, this idea was implemented: the USB-to-serial direct connection on the Raspberry Pi was replaced with a LAN-to-serial connection, which tunneled a socat virtual serial port from the home automation system to the ventilation.
With the transition to Home Assistant in 2024, it became evident that implementing socat in HAOS was challenging. As a result, the script was modified to replace serial communication with direct, socket-based communication, rendering socat obsolete.
Over the years, I have tested various LAN adapters. Below is a list of those that I successfully configured, along with their setup options. All of them have been tested to work reliably in both serial mode and socket mode.
This was my very first converter, and it operated reliably 24/7 from 2016 to 2024. To the best of my knowledge, it is no longer available for purchase. However, the manufacturer’s website lists various newer modules, including WiFi-enabled models. When choosing a replacement, make sure to select an RS485 model, NOT an RS232 one, as RS232 converters are incompatible. (Yes, the name "TCP232-304" is misleading; despite the name, this is indeed an RS485 converter, not RS232.)
All of those converters need a separate 5V DC power supply (I did not test if a step-down converter from the 24V of the ventilation would work).
Most important options are the IP settings, the communication settings (9600 8N1), the work mode 'TCP Server' as well as the local port to connect to:
The Waveshare RS485 TO POE ETH (B) was the first converter I connected directly to the 24V power supply of the ventilation system, eliminating the need for an additional power supply. It is also PoE-capable, offering great flexibility for power options. This module is designed for top-hat rail mounting, providing a cleaner and more secure installation compared to "free-floating" (=non-mounted) converters.
There appears to be a WiFi-capable "sister" module called RS485 TO WIFI/ETH (which I have not tested).
This converter has all configuration options on a single page:
This is the converter I am currently using.
It is extremely compact and features a top-hat rail mounting design. The cable terminals are well-suited for 1.5 mm² cables (e.g., standard NYM). The power supply ranges from 5–24V DC, allowing the use of the 24V DC bus supply from the ventilation system.
There also appears to be a Wifi 'sister' module, which I have not tested.
Be cautious when selecting a model — the RS232 and RS485 versions have different numbers. For RS485, you’ll need the USR-DR1x4 models (watch out for number four at the end).
The configuration is similar to the other USR model that I have in use since many years (see above). But the whole device -including the web interface- appears way more performant:
During the migration to Home Assistant, I explored also other options and discovered several ESP-based projects.
Unfortunately, none of them worked reliably enough for me, and all had only a limited set of registers / coils. Some even switched off the ventilation at unforeseeable times when a second device (like one of the above converters) was connected to the bus in parallel. However, it seems feasible to get the ventilation system online with an ESP, provided you find (or make yourself) a stable software implementation for it.
For testing, I used an ESP Nano C3 powered by the 24V supply of the ventilation system. Important: While most ESP GPIO pins are reportedly 5V tolerant, the standard operating voltage is 3.3V. Therefore, you should NOT connect the ESP directly to the RS485 bus, nor to bus power. Instead, use:
- A step-down converter for 24V → 5V to power the ESP.
- A converter RS485 → TTL (=3V3) for the A+B signal lines. This converter can be powered via the ESP's 3V3 output.
Alternatively, you can of course use an external 5V power supply, as I did in this working test setup:
However, my preference is for a wired connection. Since I could not find a stable ESP-based integration that met my needs, I chose to stick with my own implementation using the adapters listed above.