A limit switch is an example of a discrete signal.

• A. True
• B. False
• C. Not applicable
• D. Unknown

Answer: (A)

A limit switch provides a binary state—either the circuit is closed or it isn’t—when the mechanism reaches a limit. That on/off condition is a discrete signal: it has a fixed, two-state value rather than a range of voltages corresponding to varying positions. In control systems, this kind signal is what digital or discrete inputs use to represent events or positions (for example, motion stopped or a boundary hit). By contrast, a continuous signal would vary smoothly in magnitude with position, like a potentiometer or an analog sensor. So a limit switch is a classic example of a discrete signal.