Ladder Diagram Vs Schematic Diagram. There are two vertical lines. Ladder logic shares similar look and feel as relay logic.
Named so because of its resemblance to a ladder really the typical diagram consists of rails and rungs. It does not show the actual locations of the components. A ladder or line diagram is a diagram that shows the function of an electrical circuit using electrical symbols.
Below is a very simple motor control relay logic and its corresponding ladder logic.
It resemble a ladder which is why it is named ladder diagram. It resemble a ladder which is why it is named ladder diagram. A ladder diagram represents in schematic form the logical flow of electrical current. The left vertical line represents power rail voltage source while the right vertical line represents the ground or neutral.