How is a ladder diagram structured?

A ladder diagram is primarily designed to depict the flow of control in a logical, easy-to-read format that mimics the appearance of a physical ladder. Each rung of the ladder represents a specific control function, and traditionally, the outputs are placed on the right side of each rung. This structure allows for clear visualization of the relationships between inputs (often represented on the left side) and their corresponding outputs, helping operators and technicians to easily identify and troubleshoot control circuits.

The vertical lines in ladder diagrams represent the power supply, which assists in illustrating how each rung connects back to the power source. While outputs may sometimes be depicted on rungs, inputs are typically indicated alongside or before the output, providing a clearer relationship for understanding how various components interact in the control process. Complex symbols are generally avoided to maintain simplicity and clarity, which is another reason why the layout emphasizes outputs on each rung while ensuring the focus remains on the control logic rather than intricate schematics.