Page 20 - Advanced Course

KNX ADVANCED COURSE

1.4 The Write Flag ‘W’
The write flag enables the object status to be modified via the bus on the basis of a
telegram. (The object status can be overwritten). This means that an actuator can only
switch if the write flag has been set for the switch object.
The write flag is set by default for all switch objects, value objects (actuator) as well as all
push button objects (e.g. due to the update for TOGGLE functions).

Figure 13: The Write Flag "W"

1.5 The Transmit Flag ‘T’

The transmit flag enables the group object to send telegrams (transmit telegrams on the
bus). The sending of telegrams can be triggered e.g. by a push button action, a variation
in the temperature or a change in the object status. The telegram can however also be
triggered by the application program.
The transmit flag is dependent on the application and set for sensors by default. In the
case of status objects of actuators, the transmit flag is also mainly set as standard.

Home and Building Management Systems KNX Association
Flags Flags_E1212b.doc 9/13