Which statement about the PLC input interface is correct?

• A. It allows status information regarding processes to be communicated to the CPU
• B. It powers the PLC directly
• C. It handles only output signals
• D. It stores user programs in flash memory

Answer: (A)

The essential idea here is how the PLC reads signals from field devices. The input interface is where sensors and switches connect, and it condition or translate those external signals into digital information the CPU can use. In practice, it turns on/off states from the field into binary values so the processor can see the current status of the process and make decisions accordingly. The statement that best captures this is that it allows status information regarding processes to be communicated to the CPU.

It isn’t responsible for powering the PLC, which is handled by the power supply. It also doesn’t handle only output signals—that’s the role of the output interface. And it doesn’t store user programs; program memory lives in the CPU or a separate memory area, not in the input interface.