What components are contained in an analog I/O module?

• A. A/D and D/A converters.
• B. PWM generators.
• C. Networking transceivers.
• D. Relays.

Answer: (A)

Analog I/O modules are built to bridge real-world signals with the PLC’s digital processing, so the key components are the converters that handle signal translation. An analog input part uses an A/D converter to sample a real-valued signal (like a voltage or current) and turn it into a digital value the PLC can process. An analog output part uses a D/A converter to take a digital value from the PLC and convert it back into an analog signal to drive sensors or actuators. Together, they enable reading and producing continuous signals. PWM generators, networking transceivers, and relays serve different roles (pulse-width modulation, communications, and discrete switching, respectively) and aren’t the defining parts of an analog I/O module.