Dali Dimming Curve; Dali (Logarithmic) Curve - ABB i-bus KNX Product Manual

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ABB i-bus KNX
Planning and application
4.5

DALI dimming curve

4.5.1

DALI (logarithmic) curve

The DALI dimming curve does not apply for emergency lighting converters, so the curve transformation
function is not used on them.
The DALI dimming curve is adjusted to the sensitivity of the human eye. This results in a logarithmic
characteristic curve for the luminous flux which is perceived by the human eye as a linear brightness
sequence.
Note
Luminous flux describes the lighting power emitted from a light source in all directions. The unit is stated
in lumens (lm).
Luminous flux under DALI has been defined in compliance with the DALI standard (EN 6029 or
IEC 62386-102) as shown in the characteristic illustrated below.
If a DALI (logarithmic) dimming curve is selected in the gateway, the KNX value relates to the 8-bit lamp
power control value, the X value.
If a KNX (linear) dimming curve is selected in the gateway, the KNX value relates directly to the luminous
flux, the Y value.
Both are described in detail below.
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