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KNX Physical Address (Individual Address)

Every KNX device has an individual (physical) address in the format X.Y.Z, indicating its place in the topology. It is set once via ETS + programming button and is necessary for downloading the device configuration.

Format and Meaning

The format X.Y.Z represents area (1–15), line (1–15) and device number within the line (1–255). Example: "1.2.5" = area 1, line 2, device 5. Coupler devices (line couplers, area couplers) have an address with Z = 0, e.g. "1.2.0".

New devices ship with the factory address "15.15.255". This factory address must be changed to the project address before commissioning.

Difference from Group Address

Physical and group addresses are completely independent. The physical address identifies the hardware (where is the device in the network?) and is needed for the ETS download. Group addresses define the communication logic (which COs communicate with each other?).

During operation, physical addresses play no role in device control, all control runs via group addresses. Only ETS (commissioning, diagnostics) and line couplers (routing) use physical addresses.

Key Facts

  • Format: Area.Line.Device (e.g. 1.2.5)
  • Factory address: 15.15.255
  • Couplers: Z = 0 (e.g. 1.2.0)
  • Assignment: programming button + ETS download
  • Duplicate physical address → commissioning problems

Related Articles

KNX Topology
KNX TP networks are hierarchically structured: devices form a line, lines are grouped into areas, areas are connected via the backbone. This structure supports up to 14,400 devices in a pure TP network.
KNX ETS – the Engineering Tool Software
The KNX Engineering Tool Software (ETS) is the only official tool for configuring and commissioning KNX projects. Developed and maintained by the KNX Association, it runs on Windows.
KNX Commissioning
KNX commissioning is the step where ETS writes the finished configuration into the physical devices. It requires physical or IP access to the KNX bus and ETS Professional.
KNX Line Coupler and Area Coupler
A KNX line coupler (LC) connects two lines and filters telegrams, only telegrams with destination GAs in the filter table are forwarded. It reduces bus load and provides galvanic isolation.

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