An encoder is an electromechanical device that converts information (position or motion) to digital code. They are ideal for use as digital panel controls or position sensing devices. There are different types of encoders, including: contacting, non-contacting, magnetic and optical.
A programmable logic controller (PLC) is an electronic device used in many industries to monitor and control building systems and production processes. A PLC is designed to perform a single set of tasks, under real-time constraints with superior reliability and performance. To meet the demands of harsh industrial environments, PLCs are designed to be extremely robust, often capable of withstanding extreme temperatures, humidity, vibration, and electrical noise. While most commonly used for industrial manufacturing processes, the unique strengths of PLCs can make them viable for many different applications, such as a building automation system.
A relay is an electromechanical device that is actuated by an electrical current. The current flowing in one circuit causes the opening or closing of another circuit. Relays are like remote control switches and are used in many applications (telephone exchanges, digital computers, and automation systems) because of their relative simplicity, long life, and proven high reliability. Although relays are generally associated with electrical circuitry, there are many other types, such as pneumatic and hydraulic. Input may be electrical and output directly mechanical or vice versa.
A switch is an electromechanical device that is used to activate or deactivate an electrical signal. It accomplishes this function by closing or opening a set of contacts. The contacts may operate individually or in coded combinations. Switches are used to turn equipment on or off, direct signals to specific functions, or to program computerized functions on many types of electronic or electrical equipment. Common switch types include: DIP, keylock, pushbutton, pushwheel, rocker, rotary, safety, slide, snap action, and toggle.