Photoelectric sensor having indicator lamps on multiple surfaces providing coordinated indication of on-off state and workpiece detection state

A photoelectric sensor, comprising:

• a housing having a first surface and a second surface opposite to the first surface, the first surface being a top surface with a display and/or operation buttons, and the second surface being a bottom surface to which a power cable is connectable;
• the housing further comprising a third surface, the third surface being a front surface having a window through which light passes to and from the photoelectric sensor;
• and
• a first indicator lamp and a second indicator lamp configured to redundantly indicate information about a state of the photoelectric sensor,
• wherein:
• the first indicator lamp is located on the first surface, and the second indicator lamp is located on the second surface, and
• the information indicated redundantly by the first indicator lamp and the second indicator lamp includes an on-off state of a power supply to the photoelectric sensor and a workpiece detection state of the photoelectric sensor.