In the context of PLCs, what does the term "tag" refer to?

In the context of Programmable Logic Controllers (PLCs), the term "tag" specifically refers to a variable name used for data storage within the PLC. Tags are essentially identifiers that allow programmers to access and manipulate data stored in the controller. They play a crucial role in program development, as they simplify the process of referencing inputs, outputs, and internal data points in the PLC's logic.

Using tags helps create more readable and maintainable code compared to using raw memory addresses, making it easier for engineers to follow the program's logic. Tags can represent various types of data, including discrete values, analog signals, or complex structures, facilitating efficient data handling in automation applications. This variable name concept is integral to modern PLC programming languages and environments, enabling effective interaction with machine states, process variables, and user interfaces.