All Panasonic PM-45 amplifier built-in U-shaped compact micro photoelectric sensor cable type models are standardly equipped with the following protection circuits in their compact bodies. These protection circuits minimize the possibility of sensor malfunctions caused by erroneous wiring. The large operation indicator (orange) lights up when the beam enters. The indicator is easy to see from above and from the sides. The sections where stress concentrates, such as the connecting section of the cable and internal circuit, are covered with a resin. This helps prevent malfunctions caused by vibrations and impacts. The wider distance means less possibility of collision between the sensing section and sensing object. The upper-limit and lower-limit positions of beam can be visually confirmed from the front, back, right and left sides of the sensor unit. This allows easy adjustment of the position of sensing object.