Universal dimmer switch, power MOSFET up to 400W. Automatic lamp detection. Bidirectional. Standby loss only 0.3 watts. Minimum brightness and dimming speed adjustable. Includes children's room, snooze, and light alarm functions. Additionally features light scene control and constant light regulation. Rail-mounted device for installation on a mounting rail. Universal dimmer switch for lamps up to 400W, depending on ventilation conditions, dimmable energy-saving lamps (ESL), and dimmable 230V LED lamps, also depending on the lamp electronics. Circuit operates at zero crossing with soft-on and soft-off to protect the lamp. Switching voltage 230V. No minimum load required. The set brightness level is saved when switched off (memory). In the event of a power failure, the switching position and brightness level are stored and may be activated when the supply voltage returns. Automatic electronic overload protection and over-temperature shutdown. Connection to the Eltako RS485 bus. Cross-wiring bus and power supply with jumper. The upper rotary switch LA/LRN is initially needed for learning and determines during operation whether the automatic lamp detection should be active or specific comfort settings. The LED guides the learning process according to the user manual and indicates control commands during operation by briefly flashing.