Page 53 - Basic Course

KNX BASIC COURSE

12 Line-crossing telegram

Main line

LC 1 LC 2

5/2/66 5/2/66
P1 L13
0/2/11
S1

5/2/67
5/2/67
P2 L21 0/2/11

5/2/66
L11 0/2/11 L22 5/2/67

L12 5/2/66 L23 5/2/67

Figure 12: Line-crossing telegram

If the brightness sensor is not connected in the same line as the lamp it has to control, it is
necessary to transmit its telegrams via the main line.

By its parameterization, the line coupler LC2 is aware of the fact that there are bus
devices outside its own “line 2” responding to telegrams transmitted by the brightness
sensor. LC 2 therefore routes the group telegram 0/2/11 onto the main line.

Line coupler LC1 is aware of bus devices on its “line 1” that respond to the group telegram
0/2/11 and therefore transmits the telegram into its line.

All the bus devices on this line listen to the telegram from the brightness sensor but only
the actuators controlling the lights L11 and L12 execute the command.

Home and Building Management Systems KNX Association
KNX TP Topology Topology_E1213a 14/24