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DALI Bus Issues
Tools required:
•
Digital Oscilloscope 10 MHz bandwidth or greater
•
Safety Isolated Differential Probes 1 MHz bandwidth or greater
Measurements are taken between DALI wires. This method is the most comprehensive and
can uncover issues which other "static" methods (like digital multimeter test) cannot.
Important: Standard Digital Oscilloscope probes must not be used.
B
Safety Notice: DALI wiring is not touch safe. Before taking measurements ensure devices are properly
A
installed with appropriate Earthing. If unsure do not perform test and seek advice from qualified
personnel.
Using a digital multimeter, check presence of DALI power and confirm continuity/no short circuits on wiring.
Measurements are taken across DA terminals on DALI device. Expected reading in idling state: 12-21 VDC.
If the reading in idling state is between 2-12V, potential causes could be:
•
Overload (too much DALI bus load)
•
Faulty device online.
If the reading is < 2 V, there is potential wiring fault on DALI line.
When the built-in test sequence is initiated, an occasional repetitive voltage dip is noticeable on multimeter
because of data packets creating short supply interruptions. This is a normal indication of dataflow.
If potential mis-wiring or short circuit is suspected on an output or between two different outputs, a way to test
with the multimeter is to connect one DALI Bus at a time to the Controller & Power Supply side and check Bus
voltage on all DALI circuits: if any of the disconnected and unpowered DALI circuits is still returning a 12-21 VDC
reading there is likely a "cross short".
Advanced DALI troubleshooting
Tools: Digital Oscilloscope with 1 channel, min. 10MHz and Safety Isolated Differential Probes with min 1MHz
bandwidth. Standard Digital Oscilloscope probes must not be used. Measurements are (as in the previous
multimeter method) taken between DALI wires. This method is the most comprehensive and can uncover issues
which other "static" methods (like digital multimeter test) cannot.
Overall signal edges shall show a clear
and sharp rise/fall time.
Idling at 16 V must be within
12-21 V (1:20 probe used)
The time between a rising and falling
edge is 416 µS apart which equates to 2400 baud.
Signal low level must be < 4 V.
It can vary depending on type of DALI
device, physical position on network,
distance from power supply etc.
16
th
February 2022
Dynalite Hardware
.......................................
Installation Guide
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Page 19
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www.lighting.philips.com/dynalite
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