Which statement best describes the PLC chassis?

• A. A software configuration file.
• B. A physical hardware assembly that houses I/O modules, processors, and power supplies.
• C. A set of alarm routines.
• D. A communication protocol.

Answer: (B)

The PLC chassis is the physical hardware enclosure that holds all the main components of the system. It’s the metal frame or rack where you mount the processor, input/output modules, and power supplies, and it provides the backplane connections and power distribution that tie everything together. This hardware setup is what you see as the physical system you interact with in industrial control, not software.

So why this description fits: the chassis is designed to organize and support the hardware, ensuring proper electrical connections and cooling, while also allowing modules to be swapped or added as needed. It’s not a software file, a set of alarm routines, or a communication protocol—those are software concepts, whereas the chassis is the tangible, physical housing for the PLC’s core components.