KNX Group Address Structure

One of the most common questions and widely debated topics in the KNX industry is what Group Address Structure provides the best foundation for your project.

The most common structures are:

  • Function based – Lighting, Heating, Shades, etc…
  • Room based – Kitchen, Dining Room, Bathroom, etc…

In either case consistency is key to managing your project during implementation and in later years as part of a maintenance program. That being said, we prefer the Function based approach as it tends to allow for greater expansion and the ability to recall the group contents based on the Main & Middle Assignment, i.e.: 1/1/X is typically Lighting > On/Off 1Bit Control.

It is also important to consider the limitations of the GA structure during planning, as follows:

  • Up to 32 Main Groups
  • Up to 8 Middle Groups
  • Up to 256 Lower Groups
  • Totalling 65,536 GA per ETS Project File

Below we have included an example of how a function based GA structure may look:

LightingOn/Off – 1bit – Control
LightingOn/Off – 1bit – FB
LightingRelative Dim – 4bit – Control
LightingAbsolute Dim % – 1byte – Control
LightingAbsolute Dim % – 1byte – FB
LightingGeneralPIR Triggers, Locks, Blocks, etc…
HVACSetpointsBase, Current & Manual Offset
HVACModesControl & Feedback
HVACFeedbackValve Value, etc…
HVACControlWindow, Presence & Force
HVACDiagnosticsOverload, etc…
ShadingMove Up/Down -1bit
ShadingMove Step -1bit
ShadingPosition % – 1byteHeight % & Lamella %
ShadingGeneralWeather Functions
ShadingFeedbackWeather Functions

If you would like any additional information on GA Structure, please get in touch.

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