Discrete vs. Analog vs. Digital Signals

In industrial automation, we commonly encounter switching (discrete), analog, digital and pulse signals. Based on output characteristics, sensors can be classified as power-switch type (switching/discrete, e.g., "1"/"0" or "ON"/"OFF"), analog-output sensors, or digital-output sensors that produce pulses or encoded signals.

Engineers choose sensors depending on sensor type and measurement requirements, applying appropriate signal processing to obtain accurate, stable results.

Brief descriptions:

1. Discrete (switching) signals: represent on/off states and are typically passive signals. They indicate binary conditions or events and are common in proximity and photoelectric sensors, switches and buttons.

2. Analog signals: continuous quantities such as voltage, current or pressure. Typical ranges include 0–10 V or 4–20 mA and are used for measurements like temperature and pressure.

3. Digital signals: discrete signals composed of 0 and 1. After encoding, they form regular patterns used for counting, state indication and discrete data transmission.

In summary, discrete signals indicate status, analog signals convey continuous measurement values, and digital signals transmit encoded discrete data. Each type has specific use cases in electronics, automation, communication and experimental systems.