Explaining the principal differences among the graphical PLC programming languages, Yerger started with Ladder Diagram, noting its development from relay logic. “It (Ladder Diagram) looks like old ...

This programming language would use symbols encountered in conventional ladder diagrams of the hard-wired variety. The original purpose of the PLC was to allow electro-mechanical and electronic input ...

And, the ability to monitor PLC logic in ladder diagram format also made troubleshooting easier for those already familiar with relay-based control systems. Although there are many higher-level ...