Adjust the speed of dimmers/arc/scene transitions using fade rate and fade time settings

In DALI, the fade rate determines how many steps (arc levels) per second occur when an UP or DOWN command is received. Each UP or DOWN command triggers 200ms of dimming (one-fifth of a second). By default, our system is configured to 127 steps per second, which means a single UP or DOWN press will shift the level by roughly 29 arc levels. If you'd like the dimming to feel more gradual, you can lower the fade rate on the devices.

The fade time, on the other hand, controls how long a device takes to transition from its current level to a new target level when that target is set via an arc power or scene command. Note that certain commands—such as Recall Max Level, Recall Min Level, and Off—are executed immediately and are not affected by the fade time.

These settings can be configured from the Device Types → ECG view.

Note: Logarithmic Relationship Between Percentage and DALI Arc Level

DALI doesn't dim in a straight line. Instead, it uses a logarithmic curve because the human eye perceives brightness logarithmically — small changes at low light levels look dramatic, while the same change near full brightness is barely noticeable.

This means that "50%" brightness is not the midpoint of the arc level range (0–254). Arc levels are packed closely together at the dim end and spread further apart at the bright end, so each step feels like an even change to the eye.

Example values in 10% increments:

Notice how the entire lower half of perceived brightness (0.1%–50%) uses arc levels 1 through 228, while the upper half (50%–100%) only uses arc levels 228 through 254. That's why nudging a dim light up slightly looks like a big change, but the same nudge near full brightness is hardly visible at all.