DALI and DMX are popular bus systems for lighting
| Feature | DALI | DMX |
|---|---|---|
| Ideal Application | Lighting with fewer than 100 changes per day | Lighting with up to 40 changes per second |
| Dimming and fade | Smooth, 1000 steps per second | Jumpy - 40 steps per second |
| Bus ruggedness | Very high - slow bus with high noise tolerance | Very low - wiring must have exactly two ends, and each end is terminated |
| Multiple Masters | Yes - Multiple masters, multiple clients | One master, multiple clients requires a merger device for multiple masters |
| On/Off, Scene, broadcast and group support | Built-in - no master required for day-to-day operation | Requires a DMX Console |
| Power and DATA on the same bus | Yes | No |
| Topology | Tree with multiple branches | Straight line only |
| Conversion | Simple DALI to DMX converters exist | Simple DMX to DALI converters exist |
| Alexa, Schedules, Automation | User-friendly ZWD package available from ATX LED | — |
The DALI bus is a simple, 2-wire, unshielded AWG 24 or 18 daisy-chained bus for lighting control. It was developed during 2006 and is widely used in commercial applications worldwide because it has many suppliers and is tolerant of noise and installation methods. The only real design constraint is the radius length of the DALI bus from the power supply to the furthest driver distance planning.
The DALI bus allows 64 switches controlling hundreds of lights, 16 groups, and 16 scenes to be stored. A large project can have multiple DALI bus instances.
DALI to DMX
At ATX LED, our AL-WS-010v switches have the DALI bus in them and can control DMX universe devices without any master or console needed. If you want to add automation, our Hue Emulator (ATX LED Hub) provides that feature.
Why DALI dimming is better than DMX dimming
We have heard about concerns of overloading in DMX drivers. With DALI, this problem is not common, and here is why.
Too many linear ft will cause a CV power supply to overload, shut down, or burn up (unless the CV supply has CC as well). RGBW strips will overheat if the control system sets all channels to 100%. While some utilize the Overcurrent feature of Meanwell CV supplies to manage full brightness and heat in RGBW, it is not intended to operate continuously in Overcurrent mode. Overcurrent breaks the dimming curve, resulting in a DMX control slider having no effect in the top 50% of its range.
For example, if someone has an RGB strip with 24 watts per color and a 24-watt power supply and wants white, the maximum DMX value for each RGB color is 33%, resulting in only 80 steps (6 bits) of dimming resolution. A TW DMX solution like REVI requires the DMX master to limit the max value to 50% (7 bits) to avoid overheating the strip, and with 7 bits of dimming precision, the steps are visible, and dimming is imperfect.
In DALI TW, the color and brightness are set, and the driver assures that the total wattage remains constant regardless of color. DALI uses a log table, enabling far smoother dimming at low levels, closer to 12 bits of dimming resolution. Fade is built into the driver, not the control system, ensuring very smooth dimming.
In our ZWD, we treat RGBW with a complex reverse calculation of the log table (Gamma) and assure that attached Sunricher RGBW drivers will not go into overcurrent mode, allowing the expected dimming performance.