There are also the three graphical PLC languages standardized by the IEC - Ladder, Function Block Diagram, and Sequenced Function Chart. They're used everywher

There are also the three graphical PLC languages standardized by the IEC - Ladder, Function Block Diagram, and Sequenced Function Chart. They're used everywhere - anywhere you see a shiny metal cabinet with conduit running in and out, there's a chance there's a PLC plugging away in there. Ladder dates back to the 70s and I'm willing to bet is the most used graphical language in existence. It looks like the relay diagrams that electricians use.