Just like an Ice Cream Stand should never run out of chocolate and vanilla, your industrial controls partner should have basic industrial controls ready when you need them.
The Common Components of Basic Industrial Controls
Every piece of modern industrial equipment has some form of pilot device, power supply and network component on it. These devices allow operators to control the equipment, and the equipment to "communicate" with the operator. Because they are so commonly used, the number of devices present in even a small manufacturing facility is large, and being such an important part in the production environment, when these items fail, replacing them quickly is a high priority.