Page 22 - Advanced Course

KNX ADVANCED COURSE

1.5.1 Example of a Transmit Flag

Figure 15: Example of a Transmit Flag wrong
Two dimming actuators should be switched in parallel. In the following example, the
transmit flag has been set for both dimming actuators. As a result, the bus is put under a
heavy load by the respective response telegrams and the dimmers no longer react.

1.6 The Update Flag

If the update flag is set, a response telegram of a read procedure is interpreted as a write
telegram i.e. the object status of the bus device is changed. The selection and evaluation
of the update flag can only be carried out by BCU 2 bus couplers and BIM 112.
BCU 1 bus couplers always interpret response telegrams as write telegrams and
therefore modify their object status.

Home and Building Management Systems KNX Association
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