Phoenix Contact PLCs

Programmable Logic Controllers (PLCs) are computer control systems that detect the state of all input devices connected to it, make a decision based on a user-created program and then, output commands to any devices connected to it. PLCs monitor, control and communicate automated processes and act as the physical interface between devices and a SCADA or HMI system. PLCs are best suited for simpler processes and smaller automation projects that do not require rapid scalability. They are ideal for both simple and high-speed machine control and can be found in assembly equipment, motion control and dispensing systems.

Input/Output (IO) is central to every PLC. Input is the energy or information that enters a system and is usually related to sensors, switches, potentiometers, and so on. Output is the energy or information that leaves a system and is usually related to lighting devices, electric motors, alarms and so on. Both digital and analog IO are fundamental in automation technology. Digital IO is binary in nature and can either be ON or OFF. Digital input devices are push-buttons, light switches and proximity switches. Digital output devices are relays, motors starters and lights. Analog IO is a time-varying signal and has a range of values. An analog input into the PLC can increase or decrease in very small increments and the PLC can produce an analog output that acts the same way. Analog input devices are pressure sensors and temperature sensors. Analog output can be used to control the power output on a generator or the position of a needle on an analog pressure meter.