Now that we’ve covered what KNX is and how it differs from conventional installation, it’s time to look at the system itself — its specification. In this article, we’ll walk through the four KNX media (the physical ways KNX data travels), where each one is best applied, the two configuration modes available on KNX devices, and finally the concept of interworking that makes multi-vendor KNX installations possible.
This is the technical foundation you’ll need before diving into topology, telegrams, and device-level details in later chapters.
4.1 KNX Media: How KNX Data Travels
As explained in the previous article on KNX vs conventional installation, the exchange of KNX data between devices is typically done via a separate control cable. But that’s not the only option.
KNX data can also be transmitted through:
- Twisted Pair (TP) — via a separate control cable (the most common medium)
- Powerline (PL) — via the existing 230 V cable
- Radio Frequency (RF) — wirelessly
- IP — via Ethernet or WiFi
Beyond these four, KNX telegrams can also be transmitted over other media — such as optical fibre — through appropriate gateways.
When connecting different media together, suitable media couplers must be used. The medium a device supports is always indicated on the product’s label — so always check the label before assuming compatibility.
If you’d like a higher-level view of how KNX fits into building automation, see our complete overview of the KNX smart building standard.
4.2 Areas of Application for the Various Media
Each medium has its own strengths, and choosing the right one depends on the specific project. The table below summarizes the four KNX media, how each transmits data, and where each is best applied:
[Figure 5: Areas of Application for the Various Media]
| Medium | Transmission via | Preferred Areas of Application |
|---|---|---|
| Twisted Pair | Separate control cable | • New installations • Extensive renovations • Highest level of transmission reliability |
| Powerline | Existing network (Neutral conductor must be available) | • If no additional control cable can be installed • When 230 V cable is available |
| Radio Frequency | Radio line | • When no cables can be installed |
| IP | Ethernet / WiFi | • In large installations where a fast backbone is needed • For communication with mobile devices |
In short:
- Twisted Pair is the default choice for new builds and renovations where reliability matters most.
- Powerline is a practical solution when no new cable can be pulled.
- Radio Frequency is ideal for retrofits where cabling isn’t an option at all.
- IP is best suited for large-scale backbones and integration with mobile devices.
4.3 Types of Configuration: E-Mode and S-Mode
Depending on what is marked on a device’s label, KNX devices can be configured — that is, linked and have their parameters set — through two main approaches:
Easy Installation Techniques (E-Mode)
- Configuration is done without a PC, using a central controller, push buttons, or similar tools
- Intended for the skilled contractor with basic bus knowledge
- Easy-compatible products typically offer limited functionality
- Best suited for medium-sized installations
System Installation Techniques (S-Mode)
- Design and configuration are done via a PC running the manufacturer-independent ETS software
- Manufacturer product data is imported into ETS
- Intended for KNX-certified building designers and contractors
- Best suited for large installations
LTE and Dual-Mode Devices
Some devices support both configuration approaches. For example, products with the LTE label (Logical Tag Extended) are normally configured via LTE mechanisms — however, all of them include a defined S-Mode interface, which allows linking them with S-Mode-compliant devices.
This flexibility is one of the reasons KNX can serve such a wide range of projects, from small retrofits to large commercial buildings. The ETS software itself is covered in more depth in later chapters.
4.4 KNX Interworking: Why Multi-Vendor Systems Work
Interworking is the concept that makes KNX truly manufacturer-independent. Devices from different manufacturers and different functional areas — as long as they carry the KNX trademark and use the same configuration mechanism — can be linked together to form a functioning installation.
This is possible thanks to KNX standardization in two key areas:
- Telegrams — Devices usually use standard telegrams for transmission. In exceptional cases, they may also use telegrams with extended length to transmit bulky data.
- Useful data in telegrams — For various functions — including switching, dimming, shutter control, and HVAC — KNX-certified devices must use predetermined formats.
Together, these standards ensure that a KNX device from one manufacturer can understand and respond correctly to a telegram from another manufacturer — no proprietary translation layer required.
If you’d like to see how interworking fits into the bigger picture of international standardization, see our article on KNX as an international standard.
📌 Key Takeaways
- KNX supports four main media: Twisted Pair (TP), Powerline (PL), Radio Frequency (RF), and IP (Ethernet/WiFi).
- Other media — such as optical fibre — are also possible via gateways, and different media are connected using media couplers.
- The medium a device supports is shown on the product label.
- TP is best for new builds and renovations; PL works without additional cabling; RF is ideal when no cables can be installed; IP suits large backbones and mobile device integration.
- KNX devices can be configured via E-Mode (no PC, limited functionality) or S-Mode (via ETS, for large installations).
- LTE-labeled devices can be configured via LTE but also include an S-Mode interface.
- Interworking — thanks to standardized telegrams and data formats — allows devices from different manufacturers to work together seamlessly.
- New to KNX? Start with our complete overview of the KNX smart building standard.
