Industrial Relays have been used in Automation for decades. These fundamental building blocks of electrical circuits allowed the first automated systems to function without the need of modern PLCs and computers. Although you won’t find any relay based logic circuitry today, they still play an important role in modern control systems.
This is a companion discussion topic for the original entry at https://www.solisplc.com/tutorials/industrial-relay-control-system-wiring-a-24-vold-dc-relay-circuit