The classic mercury thermometer is also a type of sensor that is used to measure temperature. A sensor is a device that converts the physical phenomenon into a measurable electrical signal.įor example, an elevator gets to the floor through the installation of positioning sensors a washing machine is equipped with a sensor that measures the rpm of the motor or the water level in the drum a twilight light a TV remote control. The measurement of a physical phenomenon, such as temperature, sound level, vibration of motion oscillatory, or wind speed, begins with a sensor. Both feedback and actuators are missing in this figure as they are not the subject of this chapter.ĭetail of the complete acquisition scheme.Īt the sensor output, the electronic chain includes a “signal conditioning circuit”, a multiplexer, the sampling circuit and finally the A/D converter. The sensor is the device sensitive to the physical feature, the analog-to-digital conversion system, and the computer on which the SW architecture for managing the information is developed. Data acquisition systems are generally referred to by the acronym DAQ (Data AcQuisition).įigure 1 shows the electronic chain to acquire an analog signal. In all control systems the “heart” of the process is the data acquisition that plays a main role but at the same time it must be accompanied by a simple and intuitive user interface, the HMI-Human Machine Interface. “Data acquisition” means data exchange in both directions: from the process to the system and vice versa. All this allows both the correct processing of data and a fast action on the control system through its actuators (motors, LEDs, speakers, etc.).
The goal is to acquire data that are consistent over time and that correctly describe the shaping of the physical process. When the engineer is interested in controlling a physical process (light intensity, sound analysis, mass measure, position check, velocity, PID control, etc.) his first problem is to acquire the right information coming from one or more sensors, in some cases we talk about sensor strings or distributed sensors. The field of application ranges from research to automation, from industry to home automation, basically everything that in some way must be performed without human supervision.ĭata acquisition systems are primarily used to measure physical phenomena such as: temperature, voltage, current, strain and pressure, shock and vibration, distance and displacement, RPM, angle and discrete events, and weight. Data acquisition is a function that has a role of fundamental importance in the functions of automatic supervision and control because it relates the system (software and hardware architecture) with the process to be controlled (real world).
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