What part of a ladder diagram is shown at the start of each rung to describe the logic being executed?

• A. Coils
• B. Outputs
• C. Timers
• D. Comments

Answer: (D)

Describing what a rung does with a comment placed at the start of the rung is a documentation practice in ladder diagrams. That text doesn’t affect how the PLC runs or how the logic is executed; it’s purely for human understanding. The actual runnable part of the rung is the left-hand inputs (contacts) and the right-hand outputs (coils or other actions). Timers and other function blocks live in the rung to implement behavior, but the descriptive line at the start serves as a label for what that rung is accomplishing. So, using a comment at the start of each rung to state the logic being executed is the best fit.