A proximity sensor detects the presence of nearby objects without physical contact. Presence sensors are discrete output devices. Typically, a magnetic proximity sensor is used to detect when an actuator reaches a specific position by sensing a magnet located in the actuator.
It is not a good idea to purchase actuators from one company and magnetic proximity sensors from another. While the sensor manufacturer may say the sensor is compatible with X, Y, and Z actuators, the reality is variations in magnets and mounting positions can cause sensing issues. For example, the sensor may activate when the magnet is not in the correct position or it may not activate at all. If the manufacturer of the actuator offers a matched proximity sensor, it should be the firstchoice sensor.
Transistor-based proximity sensors have no moving parts and long service lives. Reed-based proximity sensors use a mechanical contact, have shorter service lives, and cost less than transistor models. Reed sensors are best applied in high-temperature applications and applications where ac power supply is needed.