Programmable Logic Controllers Principles And Applications By John W Webb.pdf -

—a gray, unassuming box that promised to replace miles of copper wiring with a few lines of code.

For an overview of PLC history, you can read the article on c3controls.com. Programmable Logic Controllers (PLC) | What is a PLC? —a gray, unassuming box that promised to replace

Connect the PLC to sensors, switches, motors, and solenoids. 3. Relay Logic and PLC Programming —a gray, unassuming box that promised to replace