Industrial Maintenance Technician Practice Test 2025 - Free Maintenance Technician Practice Questions and Study Guide

Proximity switches are designed to detect the presence or absence of an object without direct contact, making them ideal for use with PLC (Programmable Logic Controller) discrete inputs. Discrete inputs in a PLC are used to read binary signals—either on or off—indicating the state of various devices and conditions in a system.

Proximity switches generate a discrete signal (either activated or not activated) that corresponds with the object detection, which a PLC can interpret effectively. This functionality allows for precise control and monitoring in industrial automation systems. In scenarios where objects need to be detected without physical contact, such as in conveyor systems or automated assembly lines, proximity switches are often employed.

While indicator lamps and solenoid valves serve important functions, they primarily act as outputs that the PLC controls rather than as discrete inputs that provide state information back to the PLC. Analog sensors, on the other hand, typically provide a range of values rather than a simple on/off signal, which does not fit the discrete input nature required by the question.