Addressing & Configuration
Why do I have duplicate DALI short addresses, and how do I fix them?
By Lichtvision Engineering · Published · Updated
Short answer
A duplicate short address means two or more devices carry the same address (0 to 63), so the controller can't tell them apart and control becomes unpredictable. Duplicates show up clearly in a ProbitSite SmartScan. With Expert Mode, isolate the conflicting devices one at a time, assign each a unique short address, and re-scan after every change, without re-commissioning the whole bus.
What a duplicate short address is
Each device on a DALI line should carry a unique short address in the range 0 to 63. The short address is what controllers use to address an individual luminaire, sensor or push-button. When two devices share the same short address, both will respond to commands meant for one, both will report status when polled, and the controller cannot tell them apart. The result is unpredictable behaviour: lamps flicker, sensors trigger the wrong scene, and group programming silently fails.
How duplicates appear
Duplicates rarely come out of a clean first commissioning. The usual sources are: a second batch of luminaires installed later and addressed manually starting at 0; two segments of an installation that were commissioned separately and then physically joined; replacement drivers fitted in the field with their factory default address; or a controller that has lost its configuration and re-addressed only part of the bus.
How to spot it
A ProbitSite SmartScan shows duplicate short addresses clearly, listing every device by short address, random address and GTIN. When two rows share the same short address you know immediately that a conflict exists, which addresses are affected, and roughly how many devices are involved. There is no need to compare manual lists from the controller against the installation.
How to fix it without a full re-commissioning
With ProbitSite's Expert Mode enabled, you isolate the conflicting devices one at a time, assign each a unique short address from the free pool (0 to 63), and re-scan after every change to confirm the conflict is gone. The rest of the bus, groups, scenes, and sensor bindings remain untouched, so there is no need to re-commission the whole line or rebuild the controller project. For larger duplicates affecting many devices, it is usually faster to identify the offending segment, assign a contiguous range, and document the change in the controller project afterwards.
Avoiding duplicates in the future
Plan a contiguous address range for every batch of new luminaires, never start a manual re-address at 0 on a populated bus, and run a SmartScan after every commissioning step so that conflicts are caught on the day they are introduced.
Diagnose DALI issues like this in seconds
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