What does AO stand for?

• A. Analog Output
• B. Analog Input
• C. Automatic Output
• D. Analog Output Signal

Answer: (A)

AO stands for Analog Output. In control-system and PLC labeling, AI denotes Analog Input and AO denotes Analog Output, while DI and DO refer to Digital Input and Digital Output. An Analog Output channel is provided by a DAC inside the controller to generate a continuous voltage or current signal (like 0–10 V or 4–20 mA) that drives actuators or process controllers. This distinguishes it from Analog Input, which reads a continuous signal from sensors. The other options aren’t standard designations: Automatic Output isn’t used in this context, and Analog Output Signal describes the produced signal rather than the channel designation.