ABB i-bus KNX Product Manual page 90


ABB i-bus KNX
Commissioning

no: The lighting curve is unchanged. The DALI lighting curve as it is stipulated in the DALI standard
(EN 62386 and EN 60929) is used unchanged for the control of DALI devices
For further information see:

yes: linear lighting curve: The KNX value range is converted to the DALI value range, so that a linear
relationship between KNX values and DALI values (electronic power on the lighting equipment or
luminous flux) results. The logarithmic DALI curve is thus converted to a linear representation. In this
way, ballasts with an applied minimum dimming value (in other words luminous flux) of 3 % can be
controlled exactly with this value. Should the logarithmic DALI curve be applied, the KNX value of 50
% would be applied in this case.
For further information see:

yes: linear light. curve, without phys-min bright. value: The KNX value range (1...255) is converted to
the DALI value range (physical minimum...254), whereby the unusable range of DALI control values
(0...physical minimum), which the lighting equipment cannot realized, is omitted.
For further information see:
Note
Characteristic adjustment can only be carried out correctly if brightness value is calculated internally
with characteristic adjustment via the DALI Light Controller, simulated, and provided to the DALI
devices. This is the case e.g. when setting the brightness value.
When dimming, irrespective of whether this is via a group or a central command, differences can occur
between the set brightness value and the simulated status of the brightness value. To make it possible
to obtain equal dimming, the DALI commands DIM-UP and DIM-DOWN must be used on the DALI Light
Controller. These commands trigger a dimming step in the DALI device, which is then transformed into
the DALI characteristic on the DALI device. As the exact length of the dimming step is unknown,
deviations can arise between the calculated (simulated) value and the actual set brightness value.
This can become apparent if, after dimming, the brightness value status is fed back directly to the
dimmed lighting group as the brightness value. Where this is the case, it can result in a jump in
brightness.
88 2CDC507128D0202 | DLR/A 4.8.1.1
DALI lighting curve, page 191
DALI lighting curve, page 191
DALI lighting curve, page 191