The detection modes of photoelectric sensor are divided into the following categories: opposite type, reflective plate type, polarizing reflective plate type, direct opposite type, wide beam type, focused mode, fixed-field type and adjustable-field type. Ultrasonic sensor includes two detection mode of opposite type and proximity.
Opposite type
Transmitter and receiver of the opposite detection mode are installed in an opposite mode, the light from the transmitter aims at the receiver directly. When the object blocks the beam, output of the sensor changes to indicate that the detected object is detected.
Reflective plate type
In the reflective plate detection mode, a sensor has both transmitter and receiver. The light emitted from the transmitter shines upon the reflective plate, the reflected light returns to the receiver. When the object blocks the beam, the detected object is detected.

In addition to comprehensive parameter testing and effective screening of relays, proper use of relays is also an effective way to improve the reliability of relays. Conversely, improper use will shorten the life of the relay. How to improve the reliability of the relay? Here are some suggestions for your reference.
