KNX Group Addressing

In KNX building automation, group addressing is a foundational concept that determines how devices communicate and interact. Despite its importance, many integrators default to the structure they were initially taught, often overlooking the advantages of a more strategic approach. A thoughtfully designed group address structure not only simplifies programming but also enhances clarity, scalability, and troubleshooting efficiency.  

This article explores the key methods of structuring KNX group addresses—primarily room-based and function-based approaches—along with practical tips and conventions for labelling and organizing group addresses in residential and commercial projects. 

Two approaches to Group Addressing 

Room based approach 

This type of group address structure is focused on location, with the main group usually referencing a floor or an area. The middle group specifies the room and contains all functions relevant to that room, 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. 

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

Function based approach 

With a function based group address structure, the main group usually refers to the type of function, such a lighting, HVAC, blinds. 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. 

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. 

Group Address Labelling and Abbreviations 

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. 

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 in 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 

Group addressing tips for using the room/location based model 

When using the room/location model of group addressing, it is worth bearing in mind that only 8 middle groups are available. This means that if there is an area with more the 8 rooms, then the area may need to be split over multiple main groups (see example below). 

In the example below, we also have a group addresses for whole room control, that are associated with multiple channels and can be used to turn on or off or dim all lights in a room at once. 

Having a clear structure for group addresses can speed up linking to channels as ETS will autofill with the next available address. It is also possible to select multiple group objects at the same time and link them all to the same group address with just a few clicks. The example below shows the channels of a dimming actuator and the group addresses that it is linked to. 

Planning your Group Address Structure 

When using an external controller or visualization product, such as the Gira X1 or ABB SmartTouch, it is important to add all group addresses 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.  

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. 

Final Thoughts

A well-planned KNX group addressing structure is essential for efficient programming, easier maintenance, and faster troubleshooting. Whether using a room-based or function-based approach, consistency in layout, naming, and abbreviation practices significantly enhances project clarity and scalability.  

Room-based structures are often best suited for residential projects due to their intuitive layout, while function-based structures can offer greater efficiency in larger, more complex commercial environments. Taking the time to properly plan your group addresses, especially when integrating with external controllers, will ultimately lead to a smoother commissioning process and a more robust KNX system. 

What next?

Looking for more technical articles? Browse our other Essential Guides.
Looking for help with KNX System Design? Get in touch with our team by calling 03333 079 100 or email sales@ivoryegg.co.uk