Page 125 - Basic Course

KNX BASIC COURSE

3.2.5 Reply Telegram

Figure 4: Reply telegram

The reply telegram is produced as a result of the received telegram and must reach the
transmitter after a certain period of time. Compared to KNX-TP, only two reply telegrams
are transmitted:

ACK: Transmission was successful.
NACK: Transmission was not successful. This reply telegram is only used by the
system coupler.
If the reply telegram is not sent, the telegram is repeated. The further process is
dependent on whether the system contains a system coupler or not.
The reply telegram may not be sent by all addressed devices but only by one actuator per
group address. For this purpose, one group object must be configured as the ‘group
speaker’ during the planning stage.

Home and Building Management Systems KNX Association
KNX Powerline PL 110 Powerline_E0814a 7/17