Ladder Diagram (LD)

A Ladder Diagram (LD) is a visual programming language used in automation and control systems, especially for programming programmable logic controllers (PLCs). It resembles an electrical circuit schematic, with vertical lines called "rails" and horizontal lines called "rungs." Each rung represents a control process, showing how inputs (like switches or sensors) connect to outputs (like motors or lights). When inputs meet certain conditions, the connected outputs activate, enabling automated control that mimics electrical wiring logic. LD is valued for its clarity, making it easier for engineers and technicians to design, troubleshoot, and maintain automation systems.