Which technology is integral to the functioning of a programmable logic controller (PLC)?

A programmable logic controller (PLC) is designed to automate industrial processes by receiving inputs, processing them, and producing outputs based on a predefined set of conditions. Each of the listed technologies plays an essential role in this function.

Analog sensors provide continuous data regarding variable conditions in the system (like temperature, pressure, or flow) that the PLC can interpret to make real-time decisions. Discrete inputs, such as switches or relays, offer binary information (on/off states), which is equally crucial for the PLC since many control tasks rely heavily on these simple, clear signals. Digital signal processing can enhance the ability of a PLC to handle complex control algorithms and signal interpretations, allowing it to manage more sophisticated inputs and control strategies effectively.

Given that a PLC relies on a combination of these technologies to operate effectively, the inclusion of all three in the answer highlights their collective importance in the functioning of a PLC. This makes the chosen answer valid as it encompasses the full spectrum of integral technologies that contribute to the operational capabilities of a PLC.