PLCs are modular and consist of which of the following parts?

PLCs are modular and consist of which of the following parts?

• A. Input, outputs, CPU
• B. PCB, terminal block, CPU
• C. Inputs, outputs, CPU
• D. I/O board, hard disk

Answer: (C)

PLCs are designed around three functional blocks: the signals it receives from the field (inputs), the processor that runs the program (CPU), and the signals it sends out to control devices (outputs). This trio—inputs, CPU, and outputs—captures how a PLC interfaces with the real world and performs logic and control. The other descriptions don’t fit that structure: a PCB or hard disk isn’t what defines a PLC’s modular setup, and an I/O board without a CPU wouldn’t describe the controller’s processing role.

PLCs are designed around three functional blocks: the signals it receives from the field (inputs), the processor that runs the program (CPU), and the signals it sends out to control devices (outputs). This trio—inputs, CPU, and outputs—captures how a PLC interfaces with the real world and performs logic and control. The other descriptions don’t fit that structure: a PCB or hard disk isn’t what defines a PLC’s modular setup, and an I/O board without a CPU wouldn’t describe the controller’s processing role.