Which statement best describes the PLC output interface?

• A. Accepts field signals and converts them for the processor
• B. Converts controller signals into external signals used to control the machine
• C. Monitors internal memory health
• D. Logs data to external storage

Answer: (B)

How a PLC drives external devices is what the output interface is about. The processor makes decisions in the form of on/off states, and the output interface translates those into the actual electrical signals that energize relays, contactors, valves, or motors. It provides the proper voltage or current, the correct polarity, and any necessary isolation or protection, so the field devices respond reliably. That’s why describing it as converting controller signals into external signals used to control the machine is the best fit.

The other functions described are different roles: accepting field signals for the processor is what the input interface does; monitoring internal memory health is a diagnostic task; logging data to external storage is data logging, not driving the machine.