In ladder logic, what determines the output state on a rung?

In ladder logic, what determines the output state on a rung?

• A. The status of the contacts on the rung.
• B. The color of the wire.
• C. The shape of the coil.
• D. The environmental temperature.

Answer: (A)

The output state on a rung is determined by the status of the contacts on the rung. As the rung is scanned, each contact represents an input condition: closed (true) contacts allow the signal to pass, while open (false) contacts block it. The coil on the right energizes only when the path formed by those contacts evaluates to true—i.e., all required contacts are satisfied (or the correct parallel paths are met). If that logical path isn’t satisfied, the coil remains de-energized. The color of the wire, the shape of the coil, or environmental temperature do not determine the rung’s output state; they’re not part of the logical evaluation.

The output state on a rung is determined by the status of the contacts on the rung. As the rung is scanned, each contact represents an input condition: closed (true) contacts allow the signal to pass, while open (false) contacts block it. The coil on the right energizes only when the path formed by those contacts evaluates to true—i.e., all required contacts are satisfied (or the correct parallel paths are met). If that logical path isn’t satisfied, the coil remains de-energized. The color of the wire, the shape of the coil, or environmental temperature do not determine the rung’s output state; they’re not part of the logical evaluation.