What is the primary purpose of a PLC?

• A. To replace human operators
• B. To control equipment and processes via programmable memory
• C. To store video feeds
• D. To manage networks

Answer: (B)

A PLC is a rugged, industrial computer designed to automate machinery and processes. Its primary purpose is to control equipment and processes by executing a program stored in its memory. It continuously scans inputs from sensors and switches, applies the logic of the stored program, and sets outputs to actuators like valves, motors, and relays. This arrangement provides deterministic, real-time control essential for automation systems, handling sequencing, timing, and interlocking tasks. While PLCs can be networked and monitored, and operators may interact with them, they are not meant to replace human operators, nor are they primarily used to store video feeds or manage networks. The main function is to implement control logic on programmable memory to drive plant equipment efficiently and reliably.