In a PLC-controlled system, Timers and Counters appear as which type of functions?

In a PLC-controlled system, Timers and Counters appear as which type of functions?

• A. Input
• B. Internal
• C. Processing
• D. Output

Answer: (D)

Timers and counters are internal function blocks inside the PLC. They live in the PLC’s program memory and carry out timing and counting operations as the control logic runs, rather than representing external hardware like sensors or actuators. They respond to rung activations, hold state across scans, and provide status outputs (such as done or count reached) that other parts of the program use to drive actions. Since they operate inside the PLC to manage sequencing and timing rather than serving as external I/O, they’re best categorized as internal functions.

Timers and counters are internal function blocks inside the PLC. They live in the PLC’s program memory and carry out timing and counting operations as the control logic runs, rather than representing external hardware like sensors or actuators. They respond to rung activations, hold state across scans, and provide status outputs (such as done or count reached) that other parts of the program use to drive actions. Since they operate inside the PLC to manage sequencing and timing rather than serving as external I/O, they’re best categorized as internal functions.