The SBL1 is a Retroreflective Photoelectric Sensor with interchangeable components. The 17562 MULTI-BEAM® sensor is compact modular self contained photoelectric switches. Each MULTI-BEAM consists of three components scanner block, power block and logic module. The scanner block contains the complete modulated photoelectric amplifier as well as the emitter and receiver optoelements. It also contains the sensing optics and the housing for the other two modules. The power block provides the interface between the scanner block and the external circuit. It contains a power supply for the MULTI-BEAM plus a switching device to interface the circuit to be controlled. The logic module interconnects the power block and scanner block both electrically and mechanically. It provides the desired timing logic function (if any) plus the ability to program the output for either light or dark-operate.