Essential Guide

KNX Group Addressing

There are two main schools of thought when it comes to the layout of the Group Address structure in ETS - Room or Function. In either example the Main Group is used to split up the technologies, such as HVAC, lighting, blinds, 

Room - This groups all functions relevant to the room into one middle group meaning it is very quick and simple to program and test as everything needed for a room can be seen together. This is most suited to residential projects as the rooms define the functionality and layout of the building. It is also preferred by integrators with an AV background.

Function - This uses the Middle Group to assign the function such as switching, dimming and feedback with less regard for the building layout. This is generally more suitable for commercial projects with a large number of circuits and is preferred by integrators with an electrical or engineering background.

In either case the key is consistent use of numbering and nomenclature as this allows for an assumption to be made about the Group Address numbers once you get to know the scheme.

From the Room example - 1/0/10, 1/0/20 and 1/0/30 are switching objects for 3 circuits in the same room.

From the Function example - 3/0/10, 3/1/10, 3/2/10, 3/3/10 and 3/4/10 are the switching, dimming, value and feedback objects of the same circuit.

When using an external controller or visualisation product, such as the Gira Homeserver or ABB Comfort Touch, it is important to assign all objects that are likely to be used not just those that are needed for native bus operation. It is far easier to do this at an early stage as opposed to adding them in as needed. It also makes testing much simpler when feedback objects are assigned.

There are also various naming structures for the individual group addresses. When using the group or bus monitor it helps to have as much information as possible and in a plain text format. The following information is most helpful:

  • Room
  • Circuit Name
  • Circuit Type
  • Circuit Number
  • Wiring location
  • Function

This can be seen on both of the examples above.

Some common abbreviations used for the functions are:

  • SW - Switching
  • DIM - Brighter/darker
  • VAL or VDIM - Value dimming
  • FB - Feedback
  • VFB or VALFB - Value feedback
  • SA - Switching actuator
  • DA - Dimming actuator
  • BA - Blind actuator
  • BI - Binary input
  • HA - Heating actuator
  • MAN - Manifold
  • RAD - Radiator
  • FCA - Fan coil actuator
  • KP- Keypad
  • LK- Light keypad
  • SP - Sensor plate
  • RTR - Room temperature rollover (mode change)
  • PRS - Presence object to activate heating
  • WDW - Window object to set back heating
  • SET - Set point
  • SETFB - Set point feedback
  • IND - Indication
  • DIS - Disable

When using the standard 3 level group address structure, it is possible to have a total of 32 main groups, 8 middle groups and 256 groups

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