Which component is responsible for converting between analog and digital signals within an analog I/O module?

• A. The CPU
• B. A/D and D/A converters
• C. The memory
• D. The power supply

Answer: (B)

The thing that handles the translation between the real-world analog signals and the PLC’s digital data is the A/D and D/A converters. An analog-to-digital converter takes a continuous voltage or current from a sensor and turns it into a discrete digital value that the PLC’s CPU can process. A digital-to-analog converter does the opposite: it takes a digital value from the PLC and converts it back into a smooth analog signal to drive actuators or analog devices. Together, they bridge the analog world and the PLC’s digital realm, which is why they’re the component responsible for converting between analog and digital signals. The CPU, memory, and power supply support the system but don’t perform this conversion themselves.