Scan time is the time required to

• A. Execute one cycle of the total program
• B. Load the program into memory
• C. Initialize the CPU
• D. Communicate with HMI

Answer: (A)

In a PLC, operation happens in a repeating scan cycle. The scan time is the duration of one full cycle—from when inputs are read through to when outputs are updated. During this cycle, the PLC reads all input signals, executes the user program logic, updates timers and counters, and then writes the results to the outputs. This description best matches the idea of the time required to execute one complete cycle of the program.

Loading the program into memory is a setup step, not a cycle time. Initializing the CPU happens at power-up or reset, not during a normal scan. Communicating with an HMI is a separate I/O task that can occur within a cycle but does not define the scan time itself.