67 It has been an internationally standardised open technology since 1999 A proximity sensor is a noncontact sensor that detects the presence of an object when the target enters the sensor s field PLC SENSORS AND ACTUATORS Sensors and actuators are components of the AS-Interface , i.e. an industrial networking solution made up of cables, data access methods, and protocols used in PLC and PC-based automation systems. They are simple devices that have a far-reaching impact on industrial systems and often work together to automate industrial processes. Though they work in tandem, they are essentially opposite devices: a sensor monitors conditions and signals when changes occur; an actuator receives a signal and performs an action, often in the form of movement in a mechanical machine. Sensors A sensor is a device that detects inputs from the physical environment, such as fluid levels, temperature, vibrations or voltage, and transforms them into electrical signals. These Sensor signals are sent to the PLC in order to start, adjust, or stop Sensor the functioning of the equipment it controls. Sensor According to the kind of equipment they are connected Actuator to, different types of sensors Actuator are normally employed. The five types of sensors commonly used in control systems are: temperature sensors, pressure sensors, level sensors, flow sensors, and proximity sensors . Actuators Actuators can perform a wide range of functions, taking electrical signals from control modules (i.e. a collection of sensors that detect input from the environment) and turning them into physical outputs such as turning rotors or valves. The three main types of actuators are pneumatic (working with air pressure), hydraulic (working with fluid pressure), and electric. A good example of an actuator is a shutoff valve: when it receives a signal from a sensor or control module, it closes the valve. Pneumatic actuator Hydraulic actuator Electric actuator Sensors ONLINE RESOURCES Actuators far-reaching: ampio flow: flusso to occur: succedere, accadere shutoff: di arresto Optical Float switch Capacitance 156 ELECTRONICS AND ELECTROTECHNOLOGY Tuning fork Conductivity Ultrasonic Radar