﻿Setting the characteristic curve in the value range allows the 256 dimming steps possible on KNX to be adapted to the perception of the human eye.
If this parameter is changed, the curve of the characteristic curve is shown in the diagram below. 

The choice of characteristic curve depends on the controlled operating device and the connected lamp.

*Linear function*: In this setting, the gateway linearises the DALI dimming characteristic curve by converting all brightness values received from the KNX and projected in the ETS, appropriately into DALI data values. Thus, the KNX brightness values form linearly on the luminous flux emitted by the DALI lamps. The gateway itself does not dim linearly in this setting. A linear dimming sequence of the relative luminous flux first results at the physical output of an operating device through the combination of the non-linear conversion of the gateway and the logarithmic characteristic of the operating devices.
Status telegrams of the brightness value are also adjusted by conversion. On account of the internal calculation process, there may be slight deviations between the specified and fed back brightness value (e.g. specification = 50% -> Feedback = 49%).

*Logarithmic function*: In this setting, the gateway forwards KNX brightness values unprocessed on the DALI page. A logarithmic dimming sequence of the relative luminous flux results at the physical output of an operating device through the combination of forwarding the value of the gateway and the logarithmic characteristic of the operating devices. KNX status telegrams of the effective DALI brightness value are possible in this case too.

*Combined function*: This setting corresponds to a combination of linear and logarithmic dimming characteristic curve. The gateway converts KNX brightness values into suitable DALI dimming values, but not as intensively as with linearisation of the characteristic curve. The combination of a less severe value adjustment and the logarithmic dimming characteristic curve of the DALI operating devices results in a curved characteristic curve of the relative luminous flux at the physical output of an operating device with a less severe gradient especially in the upper dimming range. KNX status telegrams of the effective DALI brightness value are possible in this case too.

The dimming characteristic curve within the time range (relative dimming) is always linear.
