The Area/Line Coupler connects two KNX lines to form a logical functional area while providing galvanic isolation between them.
This allows each bus line within a KNX installation to operate electrically independent of the others.
The coupler distinguishes between:
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Physically addressed telegrams, such as ETS telegrams used during commissioning or application downloads.
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Group telegrams, used for communication via group addresses during normal KNX operation, for example when switching lighting.
Physically Addressed Telegrams
To forward physically addressed telegrams, the coupler must know its own physical address. This uniquely defines its position within the KNX topology.
The coupler compares the destination address of a received telegram with its own line address and, depending on the transmission direction, decides whether the telegram is forwarded.
This behavior can be configured.
Group Telegrams
The forwarding behavior for group communication can be configured separately for each transmission direction.
The following options are available:
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Forward all group telegrams.
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Block all group telegrams.
To reduce bus traffic, a filter table can also be downloaded to the coupler.
When filtering is enabled, only group telegrams whose group addresses are contained in the filter table are forwarded.
Separate settings are available for the following main groups:
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Main Groups 0–13
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Main Groups 14–31
The filter table is generated automatically by the ETS and downloaded to the coupler together with the application program or during a partial download of the group addresses.
Broadcast Telegrams
Broadcast telegrams (for example ETS management telegrams used to detect devices in Programming Mode) can be configured to be:
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Always forwarded, or
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Completely blocked.
Commissioning
When commissioning a KNX project using Area or Line Couplers, the following sequence is recommended:
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Configure the KNX installation (physical addresses, group addresses, and parameters).
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Program the physical addresses of the couplers and download their application programs.
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Program the physical addresses of all remaining KNX devices.
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Download the application programs to the sensors and actuators.
During testing, it is recommended to either:
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Set the parameters "Group telegrams Backbone Line → Line" and "Group telegrams Line → Backbone Line"to "Forward", or
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Disable the filter function directly on the device using the Pass GA button.
This prevents programmed filter tables from affecting communication during the test phase.
Finally, download the filter tables to the couplers.
The filter tables are transferred automatically when downloading the complete application or during a partial download of the group addresses.
Topology
The Area/Line Coupler forwards telegrams between a subordinate line and a superordinate line.
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Line Coupler: Line ↔ Backbone Line
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Area Coupler: Backbone Line ↔ Area Line
The operating mode is determined by the assigned physical address:
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Area Coupler (AC):
B.0.0(1 ≤ B ≤ 15) -
Line Coupler (LC):
B.L.0(1 ≤ B ≤ 15, 1 ≤ L ≤ 15)
Each KNX line has its own power supply and is galvanically isolated from the other lines.
Up to 15 lines can be combined into one area using Line Couplers.
Up to 15 areas can be interconnected using Area Couplers.
Area and Line Couplers are always logically assigned to the subordinate line.
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