A domain is a collection of KNX RF devices that are intended to work together. The maximum amount of participants is 255. RF domains are identified by the RF Domain Address (RF DoA), which consists of 6 octets (2 manufacturer specific octets + 4 random octets).
One domain can host up to 3 re-transmitters. Re-transmitters can be specific devices or it can be built in existing KNX RF devices (i.e. shutter controllers permanently directly fed by the electrical installation).
Retransmission follows mechanisms to avoid unnecessary repetitions:
S = source
D = destination
R = repeater
‘m0’: original message received simultaneously by D, R1 & R2
optimization: i.e. 2 re-transmitters = only 2 re-transmissions!