KNX

KNX is a decentralised building automation system. Devices from many manufacturers share one bus and exchange telegrams; there is no single central controller.

Media. The most common medium is KNX TP, a twisted-pair bus cable carrying both data and a safety extra-low voltage (around 30 V DC) supplied by a KNX power supply. KNX RF is the radio medium for retrofit and hard-to-wire places; KNX IP uses the building's Ethernet network, often as a fast backbone between lines and areas. Mains-voltage powerline variants have existed but are rare in new projects.

How motors are driven. In most shading projects the motor itself is a standard wired 230 V (or 24 V DC) motor. A KNX shutter or blind actuator, mounted in a distribution board or near the window, switches the motor's up and down conductors and is controlled by KNX push-buttons, weather stations, presence detectors or a visualisation. Some manufacturers also offer motors or drive controllers with a KNX interface built in. Position feedback depends on the actuator: many calculate position from travel time, some measure it, and a few motors report it directly.

Topology. Devices are organised in lines and areas with couplers, and each device gets an individual address. Group addresses link a sensor's function (for example "kitchen blind down") to one or more actuator channels.

Commissioning. Projects are configured with ETS, the engineering tool of the KNX Association. Manufacturers supply product databases for ETS, and the integrator loads parameters and addresses into each device. Training and certification for KNX partners are offered through KNX Association and certified training centres. Wiring and connection of mains devices is electrical work and must be done by a qualified electrician under local rules.

Hubs and integration. No proprietary hub is needed: the bus is the infrastructure. Visualisations, IP interfaces and gateways connect KNX to apps, building management systems and other protocols.

KNX is a multi-vendor standard. Products that carry the KNX certification mark have been tested against the KNX specification, so actuators, sensors and controls from different manufacturers can be combined in one ETS project.

• Shading motors from most manufacturers can be switched by a KNX actuator as long as the motor's wiring and electrical ratings match the actuator channel; check the motor manufacturer's guidance on parallel connection and change-over times.
• Some motor manufacturers offer KNX interfaces or gateways for their own radio systems; their documentation lists the supported functions.
• KNX IP interfaces and third-party gateways link KNX to building management systems, BACnet, smart-home apps and voice assistants; the scope depends on the gateway.
• Matter and other consumer ecosystems are reached through gateways; check each gateway's documented feature set.

KNX has no consumer pairing step; devices are configured in ETS. Typical sequence:

1. Plan the topology, individual addresses and group addresses in ETS before installation. 2. Have the bus cable, power supply and mains connections to actuators and motors installed by a qualified electrician according to local rules and the device manuals. 3. Set or check each motor's end limits as its manual describes; the actuator's travel times are then measured and entered in ETS. 4. Download addresses and parameters to each device, using the programming button or LED on the device. 5. Test each channel locally before handing over, and export the ETS project for the customer.

Pitfalls: two wired motors connected in parallel to one actuator channel can damage each other unless the motor manufacturer allows it; a missing or swapped up/down conductor reverses direction; wrong travel times make calculated positions drift. Keep the ETS project file and project password safe; without them later changes become difficult. Safety functions such as wind alarms should be configured so they cannot be overridden by ordinary push-buttons.

• Decide which medium fits the building (TP for new wiring, RF for retrofit, IP for backbone) before choosing devices.
• Check that actuators carry the KNX certification mark and that manufacturer ETS product data are available.
• Match actuator channel ratings (voltage, current, AC or DC) to the motors.
• Decide whether position or slat feedback is needed and which actuator or motor provides it.
• Plan for an integrator with ETS and KNX training, and agree who keeps the project file.
• Check which gateways are needed for apps, voice control or the building management system.