KNX Glossary: 50 Key Terms Explained

A KNX device that physically switches a load — a light circuit, a blind motor, a heating valve. Actuators sit in the electrical cabinet on the DIN rail and receive bus telegrams telling them to turn on, dim, raise or open. Without actuators, a KNX bus does nothing visible. Most homes need a switching actuator, a dimmer actuator and a blind/shutter actuator at minimum.

A logical KNX address (written as 1/2/3, "main / middle / sub") that links sensors to actuators. Press a button assigned to group address 1/1/1, and every actuator subscribed to 1/1/1 reacts. Group addresses are the glue that makes a KNX system feel coordinated.

A unique hardware identifier for every KNX device on the bus, written as 1.1.5 (line.area.device). Each device needs exactly one physical address to be reachable for diagnostics and programming. Unlike group addresses, physical addresses are not used for normal communication during operation.

The firmware-side configuration loaded onto each KNX device via ETS. It defines what the device does — how many channels it has, which datapoint types it supports, what scenes it can store. Updating the application program is occasionally needed if a manufacturer ships a feature upgrade.

The German Federal Office for Economic Affairs and Export Control. Through its energy-efficiency funding programs, BAFA partially co-finances KNX-enabled heat pump and ventilation upgrades in Germany. Relevant for DE customers only — non-DE buyers should look at local equivalents (UK BUS, FR MaPrimeRénov').

The small electronic module inside every KNX device that handles bus communication. It converts the 30 V DC bus signal into something the device's logic can use, and vice versa. In modern devices the BCU is integrated; in older sensor designs it was a swappable module behind the wall plate.

The shared low-voltage wire that links all KNX devices. KNX uses a single twisted pair (typically green, J-Y(St)Y 2x2x0.8 mm) carrying 30 V DC plus the data signal. The bus is daisy-chained, star-wired or tree-wired — no special termination required, which is what makes KNX wiring forgiving.

The umbrella term for any system that automates lighting, HVAC, shading, security and metering across a building. KNX is one of the dominant building automation standards in Europe, alongside BACnet (commercial), Modbus (industrial) and DALI (lighting-only).

The process of putting addresses into devices, loading the application program and verifying everything responds. Done in ETS from a laptop connected to the bus via a USB or IP interface. Commissioning takes a few hours to several days depending on system size — and is the part where most KNX projects either shine or stumble.

The full set of parameters defining how a KNX system behaves: which buttons trigger which scenes, what time the blinds go down, how the heating responds to presence. Configuration lives in the ETS project file, which is the single source of truth for the entire installation.

A KNX device that connects two bus segments. Line couplers join lines into an area, area couplers join areas into a backbone. In modern installations IP backbone routers do the same job over Ethernet. Couplers also act as filters — keeping noisy traffic out of quiet segments.

A dedicated lighting protocol (Digital Addressable Lighting Interface) used heavily in commercial buildings. KNX-DALI gateways let you control DALI-equipped LED drivers from the KNX bus — common in offices, less common in homes. DALI gives finer dimming control than KNX-only switching.

A KNX actuator that varies output voltage to dim lights smoothly — typically leading-edge or trailing-edge for incandescent, halogen or dimmable LED loads. Universal dimmers detect the load type automatically. A 4-channel dimmer actuator runs around 250-350 EUR.

A standardised data format for KNX telegrams — for example DPT 1.001 for switching (on/off), DPT 9.001 for temperature in °C, DPT 14.056 for power in watts. DPTs are what makes a Gira sensor and a Siemens actuator from different decades still understand each other on the bus.

The official KNX programming software, sold by the KNX Association. Every certified KNX integrator uses ETS to design, commission and maintain installations. ETS Professional costs around 1,000 EUR; smaller licences (Lite, Home) exist for limited project sizes. There is no real alternative — programming KNX without ETS is not practical.

The predecessor to KNX, in service since 1990. When EIB, BatiBUS and EHS merged in 2002, the result was rebranded as KNX. EIB devices still work on a modern KNX bus, which is why you sometimes find decades-old EIB switches still functioning alongside new KNX hardware.

The wall-mounted enclosure that holds breakers, RCDs, the KNX power supply, all actuators, the IP gateway and supporting hardware. In a KNX home it replaces the conventional fuse box and is typically larger — a 4-6 row cabinet for a single-family home is normal. More on cabinet planning.

A single automatable behaviour assigned to a room — switching, dimming, blind control, heating setpoint, presence detection. In our configurator each function adds a defined surcharge per room. Three functions per room (light, blind, heating) is the typical residential baseline.

A general term in industrial automation for a low-voltage communication wire that connects field-level devices (sensors, actuators). KNX is technically a field bus, optimised for buildings rather than factories. Other building field buses include LON and Modbus.

A wiring rule allowing daisy-chain, star and tree configurations on the same line — anything except a closed ring. KNX supports free topology, which lets electricians route the bus cable wherever it is convenient. This forgiveness is one reason KNX is easier to install than it sounds.

See "Address (Group Address)" — the logical channel that lets a sensor talk to one or many actuators at once. Group addresses are how you build scenes, central off functions and cross-room logic without rewiring.

A device that translates between KNX and another protocol — KNX-IP, KNX-DALI, KNX-Modbus, KNX-Sonos. Gateways are how a KNX system connects to the wider home ecosystem (Home Assistant, audio multi-room, weather services, heat pumps).

A major German KNX manufacturer, known for premium switch designs (Esprit, E2, System 55), touch panels (G1, X1, HomeServer) and quality binary inputs. Gira hardware is at the higher end of the price scale but is what most architects specify by default.

Software or hardware that monitors and optimises electricity flow between PV, battery, grid, heat pump and EV charger. KNX can act as the HEMS data layer, reading meters and switching loads. More on KNX + PV.

Philips Hue is a wireless Zigbee-based lighting ecosystem — cheap, plug-and-play, cloud-dependent. KNX is wired, expensive, vendor-independent. The two coexist well: many KNX homes use Hue bulbs for accent lighting and KNX for everything else.

Consumer-facing term for any system that automates lights, climate and appliances. KNX is one option; HomeKit, Z-Wave, Zigbee, Matter and Home Assistant are others. The line between "home automation" (lifestyle) and "building automation" (infrastructure) is mostly marketing.

In KNX context: the physical work of pulling bus cable, mounting actuators in the cabinet and wiring sensors. Installation is the electrician's job; commissioning is the integrator's. The two skills overlap but are not the same.

A small DIN-rail device that connects the KNX bus to Ethernet. Used by ETS for programming, by Home Assistant for integration, by mobile apps for remote access. An IP gateway runs around 200-400 EUR and is essentially mandatory in modern KNX homes.

The hardware bridge between a laptop running ETS and the KNX bus. USB interfaces are cheap (~100 EUR) and used for site work; IP interfaces are slightly more expensive but allow remote diagnostics. Every KNX project needs at least one.

German switch manufacturer with a deep KNX product range (LS990, A-series, F40 sensors). Like Gira and Berker, JUNG sits at the architect-spec end of the market. Visually iconic; their LS990 is in MoMA's permanent collection.

A KNX actuator with internal logic for raising, lowering, tilting and timing roller shutters or venetian blinds. Solar position presets, wind protection and central commands run on this device. Typical price 250-400 EUR for 4 channels.

A wired (and optionally wireless) building automation standard, originally introduced as EIB in 1990 and rebranded as KNX in 2002 after merging with BatiBUS and EHS. Published as ISO/IEC 14543-3 and EN 50090, KNX is one of the few genuinely international, vendor-independent smart home standards. Full history here.

The wireless variant of KNX, using the 868 MHz ISM band. KNX-RF is used in retrofit scenarios where bus cable cannot be pulled. Range, reliability and battery life are weaker than wired KNX, but better than most consumer Z-Wave / Zigbee systems.

An optional encryption and authentication layer for KNX telegrams (KNX IP Secure and KNX Data Secure). It protects against bus tapping and replay attacks. Required in commercial and public buildings; increasingly common in residential. Costs slightly more in hardware and ETS time.

The basic KNX topology unit — one line holds up to 64 devices and one bus power supply. Multiple lines join via a line coupler to form an area; multiple areas form the full installation. A single-family home is usually one or two lines.

A KNX device or software component that performs conditional logic — "if outside > 25 °C and blinds are open, close them". Hardware logic modules (MDT, Gira, Arcus) sit in the cabinet; software logic runs in visualisation servers or Home Assistant. Most homes need at least basic logic.

The power supply unit for LED loads. KNX dimmer actuators can dim some LED drivers directly via phase-cut, but for high-end LED lighting a KNX-DALI or KNX-0-10V gateway driving dedicated drivers gives smoother, flicker-free results.

The backbone bus segment that links area or line couplers. In modern installations the main line is often replaced by an IP backbone — line couplers act as KNXnet/IP routers and traffic runs over Ethernet between them. Faster and more flexible than the classical 9600 baud bus.

A German KNX manufacturer with strong price-to-quality ratio, often used for actuators and sensors in cost-sensitive projects. MDT's actuators are nearly universal in Piesco-built cabinets — reliable, good ETS templates, half the price of Gira equivalents.

Matter is a new IP-based consumer smart home standard (CSA-led). It is wireless, app-centric, and aimed at plug-and-play devices. KNX and Matter target different layers: KNX is the infrastructure in the walls, Matter is the consumer device protocol. They are increasingly bridged via gateways.

The US electrical wiring standard. KNX bus wiring is Class 2 / low-voltage and falls under straightforward NEC rules; the actuator side that switches 120 V mains needs a licensed US electrician. KNX is rare but legal in US installations.

Battery-backed lighting required by code in many commercial buildings. KNX can monitor and trigger emergency lighting circuits, but the safety-critical wiring must follow local code (EN 1838 in Europe, NFPA 101 in the US) — KNX is supervisory, not safety-rated.

A KNX variant that sends telegrams over existing 230 V wiring instead of a dedicated bus cable. Almost extinct in new installations — superseded by KNX-RF and IP. You will only encounter it in older European industrial retrofits.

A PIR or micro-radar sensor that detects occupancy and, on premium models, brightness and temperature. KNX presence sensors automate lighting, HVAC and security — they are the most underrated device in a KNX home. Quality ones (Steinel, MDT, Gira) run 150-300 EUR per unit.

A wall-mounted KNX sensor with one or more rockers, often combined with a temperature sensor and an LED status. Push buttons replace conventional light switches and can trigger anything — scenes, dimming, blinds, central off. Premium ranges (Gira Tastsensor, Jung F40) cost 200-400 EUR each.

A DIN-rail device that couples KNX lines via Ethernet using the KNXnet/IP protocol. Faster than classical bus couplers, supports KNX IP Secure, and is the modern default for multi-line installations. Replaces the older area / line coupler concept.

A KNX actuator that controls red/green/blue (and optionally white) LED channels for coloured accent lighting. Common applications: ceiling cove lighting, kitchen plinth strips, garden facade lighting. Typical price 200-350 EUR for a single 4-channel unit.

Wired KNX bus segments can run up to 1,000 m total cable length per line (with each device max 700 m from the power supply). KNX-RF range is around 30-100 m line-of-sight, less through walls. Both are well above what a typical single-family home needs.

The electrical enclosure that holds the entire KNX brain — breakers, RCDs, power supplies, all DIN-rail actuators, the IP gateway. We pre-build, label and test these before shipping. A finished cabinet is typically 4-6 rows wide for a single-family home.

Any KNX input device — push button, presence sensor, temperature sensor, weather station, binary input for window contacts. Sensors send telegrams onto the bus; actuators react to them. A typical KNX home has 30-60 sensors of various kinds.

A standard signalling interface (Smart Grid Ready) for heat pumps. KNX can drive SG-Ready inputs via two binary outputs, letting the heat pump shift its operation to coincide with solar surplus or cheap grid tariffs. Crucial for cost-optimised heat-pump operation.

The structural map of a KNX installation: how many lines, how many areas, where the couplers sit, where the power supplies are. Good topology design keeps each line below 60 % device load and isolates noisy segments (lighting) from quiet ones (HVAC).

A wall- or table-mounted screen for KNX visualisation — typical models: Gira G1, Jung Smart Control 19, MDT VisuControl. Touch panels are mostly a UX preference; functionally most things can also be done by the mobile app. Prices range from 800 to 3,000 EUR per panel.

In KNX context: a room temperature controller — either a dedicated wall device or a built-in feature of a KNX push button. The thermostat sends a setpoint or valve-position telegram to a heating actuator that opens/closes underfloor heating valves. Each room with a thermostat becomes a heating zone.

A small dongle (~100 EUR, MDT, Weinzierl, Tapko) that plugs into a laptop's USB port on one side and the KNX bus on the other. Used by ETS during commissioning. Cheaper than an IP interface but limited to on-site work.

The graphical front end of a KNX system: a touch panel, mobile app or web dashboard that shows what is on, what the temperature is and lets you trigger scenes. Common solutions: Gira HomeServer, Jung Smart Visu, ComfortClick Jigsaw, iRidium, openHAB and Home Assistant.

The DIN-rail unit that feeds 30 V DC into the bus. Standard models are 160 mA, 320 mA or 640 mA — sized to the number of devices on the line. Always include redundancy on safety-critical installations. Typical price 100-250 EUR.

An AC or DC electric-vehicle charger. KNX can integrate with most modern wallboxes (KEBA, ABL, go-e, OpenWB) via Modbus or KNX-Modbus gateway — enabling solar-surplus charging, off-peak prioritisation and load management against the heat pump.

A KNX-connected outdoor sensor that reports temperature, wind speed, rain, solar irradiance and sometimes brightness from up to four directions. Drives wind protection for blinds, solar shading and rainwater logic. Typical price 400-1,200 EUR depending on feature set.

A KNX device manufactured by one company and sold under another's brand. Common in the budget actuator segment — Hager, Ekinex and several others rebrand from shared OEM platforms. Quality is usually identical; price and ETS template differ.