Which components are typically part of a ladder logic rung?

Which components are typically part of a ladder logic rung?

• A. Motors and valves
• B. Inputs, outputs, and memory
• C. Sensors and actuators only
• D. Resistors and capacitors

Answer: (B)

A ladder logic rung is a small control circuit that is built from three kinds of elements: inputs, memory, and an output. The left side uses input conditions, such as sensors or pushbuttons, which determine whether the rung can be energized. In many programs a memory element—internal relays or memory bits—stores state from a previous step, enabling actions like latching or sequencing across multiple rungs. The right side contains an output coil that energizes an actuator or serves as another memory element for later rungs. This combination—inputs to represent what’s happening, memory to hold state, and an output to drive a device—captures what a rung typically contains. Motors and valves are examples of actuators you might control with an output, but they aren’t the building blocks of the rung itself. Sensors and actuators describe what you might connect to, not the fundamental components that make up the rung. Resistors and capacitors belong to the electrical hardware and are not part of the ladder logic representation of a rung.

A ladder logic rung is a small control circuit that is built from three kinds of elements: inputs, memory, and an output. The left side uses input conditions, such as sensors or pushbuttons, which determine whether the rung can be energized. In many programs a memory element—internal relays or memory bits—stores state from a previous step, enabling actions like latching or sequencing across multiple rungs. The right side contains an output coil that energizes an actuator or serves as another memory element for later rungs. This combination—inputs to represent what’s happening, memory to hold state, and an output to drive a device—captures what a rung typically contains.

Motors and valves are examples of actuators you might control with an output, but they aren’t the building blocks of the rung itself. Sensors and actuators describe what you might connect to, not the fundamental components that make up the rung. Resistors and capacitors belong to the electrical hardware and are not part of the ladder logic representation of a rung.