Thanks for the answer. But even in the web interface, I don't find any obvious way of linking the motion sensor action with the light or brightness sensor.
The motion sensor always switches on the light if a presence is detected, irrespective of day, twilight, or night.
The only thing I can change is the intensity of the light during day, twilight, or night in the Lux settings. But a value of 0 for day does nothing.
