KNX Individual Address

This information is based on the version 1.1 of the KNX specification.

KNX Address defined in the Data Link Layer is a two byte field, consisting of address high byte (a.k.a Octet 0) and low byte (a.k.a Octet 1).

The structure and semantics of these two bytes differs depending on whether a group address or individual address is being used.

KNX Individual Address

                 +-----------------------------------------------+
       16 bits   |              INDIVIDUAL ADDRESS               |
                 +-----------------------+-----------------------+
                 | OCTET 0 (high byte)   |  OCTET 1 (low byte)   |
                 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
          bits   | 7| 6| 5| 4| 3| 2| 1| 0| 7| 6| 5| 4| 3| 2| 1| 0|
                 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
                 |  Subnetwork Address   |                       |
                 +-----------+-----------+     Device Address    |
                 |(Area Adrs)|(Line Adrs)|                       |
                 +-----------------------+-----------------------+

• Individual addresses must unique.
• Each device must have an individual address.
• The Device Address byte must be unique within a subnetwork.
• Device Address 0 is reserved for a router in the subnetwork.
• Other devices have addresses in the range [1..255].

Notable is that the specification recommends (but does not mandate) the Subnetwork Address to be interpreted as shown above with Area Address and Line Address segments when hierarchical topology is used in configuration. Area address is assumed to be unique within a network where as line address is assumed to be unique within an area.