ELI5: programming language ladder

// eli5

What is ladder logic?

Ladder logic is a special way to write instructions for machines called PLCs (programmable logic controllers) that control factory equipment [2]. It's called "ladder" because the code looks like a ladder with horizontal rungs, just like the relay circuits it was based on [1].

Why does it look like a ladder?

The language was designed to match how old electrical relay systems worked, which looked like ladders [1]. Instead of writing words like regular computer programs do, ladder logic uses symbols and diagrams that electricians already understood [3].

Who uses ladder logic?

Factory workers and electricians use ladder logic to program machines that do repetitive jobs, like assembly lines or conveyor belts [2]. It's been around for over 120 years, starting long before modern computers existed [1].

Why is it still popular?

People still use ladder logic because it's easy to read and fix when something goes wrong [5]. Even if you didn't write the code, you can quickly look at the ladder diagram and understand what the machine is doing [5].