Programmable logic circuits (PLCs) are not a specific brand but a category of industrial electronic devices used for automation and control systems. These circuits are produced by various global companies, including Siemens (Germany), Allen-Bradley (a brand of Rockwell Automation, USA), and Mitsubishi Electric (Japan). PLCs are widely used in manufacturing, energy, and infrastructure industries to automate machinery and processes. Key products include programmable logic controllers, industrial computers, and modular I/O systems, which enable flexible and scalable automation solutions. These devices are essential for optimizing efficiency and reliability in industrial operations.