Page 151 - Advanced Course

KNX ADVANCED COURSE

End: The telegram is received by 1-fold switch actuator 15.15.127 which then returns a
reply telegram (ACK).
The actuator then switches its output according to the transmitted value of the
communication object.

The result of using telegram filtering is that telegrams are only passed to lines that really
require them. Telegrams are not routed to places where they have no effect. The
advantage of this is that the bus load in the installation is reduced.

Line repeaters do not filter. They should therefore not be used in the planning of a new
KNX installation but in the extension of an existing one.

The routing counter has the benefit that even when the installation has faulty wiring (loop
formation with couplers), a telegram circulates in the loop a maximum of six times. The
installation is not blocked! On the other hand, the routing counter has the effect that a
telegram can only pass through a maximum of six couplers. As a result, line repeaters
may not be connected in series.

2.6 Telegram Structure for Download of couplers

For the download of filter tables, couplers are addressed by ETS with other telegram
types (APCIs) than normal devices.

2.7 Filter Table

The filter table is created automatically by ETS.

If a coupler is marked in the Topology View or the Building View, the contents of the filter
table can be displayed via context menu through the option Preview Filter Table....
The filter table which is actually present in the coupler is obtained via the menu item
Diagnostics/Device Info... of ETS3 Professional, if the box ‘group communication’ is
ticked in the then opening dialog box.
The filter table is edited in ETS3 Professional in the following way: The Topology window
and the Group Addresses window must be open. If group addresses are now dragged
onto a line via ‘drag & drop’, a new symbol is created in this line. It has the designation
“Manual Filter Table Entries”. If this symbol is selected, the manually entered group
addresses appear on the right hand side of the window.

Note:
If an entry should be deleted, the best method is to use the context menu. It is essential
to select ‘Remove’ and not ‘Delete’. ‘Delete’ would delete the group address completely
i.e. also from the group address table and in all places it was assigned.

Home and Building Management Systems KNX Association
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