Advanced Programmable Logic Controller (PLC) Practice Test 2026 - Free PLC Practice Questions and Study Guide

Discrete signals are characterized by their binary nature, where they represent distinct states, typically expressed as 'on' or 'off', which corresponds to a digital representation (1 or 0). This binary format means that discrete signals take on finite values, making them ideal for systems where specific states need to be monitored or controlled, such as in digital electronics or PLC inputs and outputs.

In contrast, analog signals are continuous and can take on an infinite range of values within a given range. This characteristic allows analog signals to represent varying measurements, such as temperature, pressure, or speed, facilitating a more fluid and nuanced control in processes that require gradual changes rather than abrupt shifts.

This fundamental difference in how signals are represented—discrete as binary states and analog as continuous values—highlights the differing applications and functionalities of each type of signal in automation systems and controls.