DALI is luminaire-level lighting control and KNX is room-level building control. Many buildings use both, and both can be read into one data model.
Different Layers of the Same Building
DALI (Digital Addressable Lighting Interface, IEC 62386) is a lighting-specific bus. Each LED driver or ballast has its own address, so one luminaire can be dimmed, grouped or queried for faults. KNX is a general building control system for lighting, blinds, heating, ventilation and security, organized around rooms and functions rather than individual luminaires.
Addressing and Size
A DALI line carries up to 64 control gear and 64 control devices, with short addresses 0 to 63 for control gear, and a bus power supply per line typically rated up to 250 mA. KNX groups devices by group addresses such as 1/2/5, defined in the ETS project, and the meaning of each address exists only in that project.
How They Work Together
A common design uses KNX as the building backbone and DALI gateways to bring luminaire-level lighting into it. The gateway acts as the DALI application controller and exposes groups, scenes and status as KNX group objects. Faults that exist only at the luminaire, such as a lamp or driver failure, must be passed through by the gateway to be visible upstream.
What Each Exposes for Monitoring
KNX reports the state of group objects: on, off, dim level, scene. DALI can additionally report lamp failure, driver failure and, on DALI-2 D4i equipment, energy and operating hours. Which of these reach the network depends on the gateway, so check its supported objects before promising a data point.
Reading Both Together
A normalized tag model gives a KNX dim level and a DALI luminaire status the same shape, with a name, unit, timestamp and quality. IoTServa reads KNX over KNX IP and DALI through the gateway or controller, so lighting from either system can be trended and alerted on beside HVAC and energy.
Common Questions
Is DALI better than KNX for lighting?
They are not direct competitors. DALI gives luminaire-level control and diagnostics on a lighting bus, while KNX covers whole-building functions. Many projects combine them through a KNX to DALI gateway.
Can IoTServa read DALI directly from the bus?
No. DALI runs at 1200 bit/s on a line managed by a controller, so IoTServa reads the lighting data from the DALI gateway or controller over its BACnet, Modbus, KNX or MQTT interface.