PLCs on Food Lines

Words to know PLC (Programmable Logic Controller): the small industrial computer that runs a machine.Input: a signal going into the PLC, such as a sensor seeing a tray or a button being pressed.Output: something the PLC switches on, such as a motor, valve or light.I/O card: the part of the PLC where inputs and outputs are wired in. Each signal has its own light.Ladder logic: the most common way PLC programs are written. It looks like a ladder on its side.HMI: the touchscreen operators use to run a machine and see alarms. What a PLC does A PLC is the industrial computer that runs most machines on a food line. It works in a simple loop, many times a second: It reads its inputs: sensors, switches and push buttonsIt runs its program to decide what should happenIt switches its outputs: motors, valves, solenoids and lights Most UK food sites use PLCs from a handful of makers, such as Siemens, Allen-Bradley (Rockwell), Omron and Mitsubishi. The details differ, but the ideas are the same. On the shop floor Think of a…