What component does a PLC need to accept operator input?

A Human-Machine Interface (HMI) is essential for a Programmable Logic Controller (PLC) to accept operator input. An HMI serves as a user-friendly interface that allows operators to interact with the PLC and monitor operations visually. It provides a graphical display that can show real-time data, control parameters, and machine status, making it easier for operators to enter commands and settings.

When discussing the context of PLCs, it's important to recognize that while analogue input cards are used to process signals from sensors, they do not provide a means for operators to input information directly. Similarly, an internet or network connection can facilitate remote monitoring or control but does not inherently support direct operator input. Specialized software might be needed for programming or configuring the PLC but does not serve as a direct interface for operators to interact with the system. Therefore, the HMI is specifically designed to bridge the gap between the operator and the PLC, making it the correct component for accepting operator input.