Surveillance in public transportation ensures the safety of passengers and driver, and plays an important role in criminal investigation. PoE camera is commonly used on bus since it can be powered by PoE switch through the Ethernet cable and achieve data transmission. A bus company chose Korenix’s E-Mark compliant PoE switch for their project. It is rugged, plug-and-play unmanaged switch equipped with robust M12 connector design in order to be used well in the vibrating environment.