The L4000 system consists of the UE401 safety evaluation device and photoelectric safety switches. The UE401 safety evaluation device functions as the link between the photoelectric safety switches and the machine controller. It makes it possible to connect up to 4 sensor pairs (sender/receiver combination) or up to 8 cascaded sensor pairs. Color LEDs provide local information about the operational status. Quickly see diagnostic data using status and error messages on the 7-segment display of the UE401 safety evaluation unit. Even complex protection tasks can be performed due to the ability to connect up to 8 sensor pairs, a range of versions that can be selected according to requirements, suitability for outdoor applications and the use of deflector mirrors.