Integrating KNX with Home Assistant (HA) is the “gold standard” for professional-grade smart homes. While Wi-Fi and Zigbee are great for hobbyists, KNX offers a hardwired, decentralized backbone that works even if HA is offline.
To bridge these two worlds, you need a KNX IP Gateway. This guide breaks down the most popular hardware options and technical considerations for 2025.
The “Big Two”: IP Interface vs. IP Router
Before buying hardware, you must understand the distinction. Most Home Assistant users should aim for an IP Interface, but there are exceptions.
1. KNX IP Interface
- How it works: Provides a point-to-point “tunnel” from your LAN to the KNX bus.
- Best for: Standard residential setups where HA is the primary logic engine.
- HA Compatibility: Uses the
tunnelingconnection type. - Popular Models: MDT SCN-IP000.03, Weinzierl 731, ABB IPS/S 3.1.1.
2. KNX IP Router
- How it works: Acts as a line coupler. It “routes” telegrams between the IP network and the twisted-pair (TP) bus.
- Best for: Large, multi-line installations or when you need “Multicast” communication.
- HA Compatibility: Uses the
routingconnection type. - Why use it? Multiple devices (like HA and ETS) can talk to the bus simultaneously via Multicast without using up specific “tunneling” slots.
Top Hardware Options for Home Assistant (2025)
1. MDT SCN-IP000.03 (The Engineer’s Choice)
MDT is widely regarded as the best “price-to-performance” brand in the KNX ecosystem.
- Features: Supports up to 5 simultaneous tunneling connections (crucial if you want to use HA and ETS at the same time).
- Power: Powered by the KNX bus (no external PSU needed).
- Security: Supports KNX IP Secure, ensuring your automation traffic is encrypted on your local network.
2. Weinzierl 731 / 732 Secure
Weinzierl is the “OEM” for many other brands. Their devices are incredibly compact (often only 18mm wide).
- Features: The 732 model supports KNX IP Secure and is known for rock-solid stability with the HA KNX integration.
- Note: Very popular for DIN rail space-saving.
3. 1Home Bridge / Atios KNX Bridge
If you want to skip the “manual YAML” pain, these are specialized gateways designed for modern integrators.
- Key Feature: They often act as a Matter Bridge. This allows KNX devices to show up in HA (or Apple Home) via Matter, potentially simplifying discovery.
- Trade-off: significantly more expensive than a standard MDT interface.
4. The DIY Option: “TUL” or ESP32-KNX
For engineers on a budget, boards like the Busware TUL or custom ESP32+KNX Transceiver (TP-UART) setups exist.
- Warning: These require manual flashing (ESPHome or custom firmware) and are generally less reliable for critical “core” infrastructure than a DIN-rail industrial gateway.
Technical Integration Specifics
IP Secure: Should you enable it?
Modern HA (2024.x and 2025.x versions) supports KNX IP Secure. If your gateway supports it, use it. It prevents anyone on your Wi-Fi from “sniffing” or sending telegrams to your physical switches. You will need the .knxkeys file from your ETS project to set this up in HA.
The “Must-Have” Feature: Multiple Tunnels
Never buy a gateway that only supports one tunneling connection.
- Scenario: Home Assistant is connected to the gateway. You open ETS6 on your laptop to change a light switch’s behavior.
- The Conflict: If you only have one tunnel, ETS will fail to connect because HA is already “occupying” the line.
- Requirement: Look for gateways with 5+ tunneling connections.
YAML vs. UI Configuration
While Home Assistant has moved toward UI configuration, the KNX integration still relies heavily on knx.yaml.
- Pro Tip: Export your Group Addresses from ETS as a CSV or XML. Use a script (or LLM) to convert them into the HA
knx: light:orknx: sensor:format to avoid manual entry errors.
| Feature | IP Interface (e.g., MDT) | IP Router (e.g., Gira) | Bridge (e.g., 1Home) |
| Primary Use | HA Integration / Programming | Multi-line backbone | Simplified Logic/Matter |
| Bus Load | Low (Point-to-point) | Medium (Filtering tables) | Variable |
| Price | €150 – €250 | €350 – €500+ | €400 – €600 |
| HA Stability | Excellent | Excellent | Good (Matter-dependent) |
