السلام عليكم ورحمه الله وبركاته اقدم لكم تطور أنظمة التحكم الألى History of PLC During the Industrial Revolution of the 18th-and 19th-centuries, many traditionally manual processes were taken over by machines. These early machines relied on gears and pulleys to work and were, by our standards, extremely primitive. The first major breakthrough in the development of control systems came with the invention of electrically powered machines. The first control systems were developed in the early years of the 20th century and used sequential Relay Circuits for machine control. A major technical breakthrough in its day, and still used in some plants today, relay technology enabled machines to work faster and more safely. Relay circuits performed their job very well, but they required large amounts of floor space, and huge amounts of energy. Adding to their drawbacks as the basis for a machine control system, relay circuits also took a long tim...