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Acquired data is displayed, analyzed, and stored on a computer, either using vendor supplied software, or Custom Displays and control can be developed using various text-based Programming Languages such as BASIC , C , Fortran , Java , Lisp , Pascal . EPICS is used to build large scale data acquisition systems. Comedi is an open source project that defines a application programming interface and driver structure. It is a standard programming method to access data acquisition hardware. LabVIEW offers a graphical programming environment optimized for data acquisition. MATLAB provides a programming language but also built-in graphical tools and libraries for data acquisition and analysis. HOW DATA IS ACQUIRED Data acquisition begins with the Physical Phenomenon or Physical Property of an object (under investigation) to be measured. This physical property or phenomenon could be the temperature or temperature change of a room, the intensity or intensity change of a light source, the pressure inside a chamber, the force applied to an object, or many other things. An effective '''data acquisition''' system can measure all of these different properties or phenomena. A Transducer is a device that converts a physical property or phenomenon into a corresponding measurable electrical signal, such as voltage or current. The ability of a '''data acquisition''' system to measure different phenomena depends on the transducers to convert the physical phenomena into signals measurable by the data acquisition hardware. Transducer s are synonymous with Sensors in DAQ systems. There are specific ''' Transducers ''' for many different applications, such as measuring temperature, pressure, or fluid flow. Signals may be Digital (also called '''logic signals''' sometimes) or Analog depending on the tranducer used. Signal conditioning may be necessary if the signal from the transducer is not suitable for the DAQ hardware to be used. The signal may be amplified or deamplified, or may require filtering. DAQ hardware is what usually interfaces between the signal and a PC. It could be in the form of modules that can be connected to the computer's ports ( Parallel , Serial , USB , etc...) or cards connected to slots (PCI, ISA) in the Mother Board . DAQ-cards often contain multiple components (multiplexer, ADC, DAC, TTL-IO, high speed timers, RAM). These are accessible via a Bus by a Micro Controller , which can run small programs. The controller is more flexible than a hard wired logic, yet cheaper than a CPU so that it is allright to block it with simple Polling Loops . For example: Waiting for a trigger, starting the ADC, looking up the time, waiting for the ADC to finish, move value to RAM, switch multiplexer, get TTL input, let DAC proceed with voltage ramp. Driver software that usually comes with the DAQ hardware or from other vendors, allows the operating system to recognize the DAQ hardware and programs to access the signals being read by the DAQ hardware. HISTORY Scientific Solutions --> link Scientific Solutions invented the PC based data acquisition in 1981 with the introduction of the LabMaster, '''BaseBoard''','''DADIO''','''LabTender''', '''IEEE-488''' hardware and '''LabPac''' software. Scientific Solutions was formally a part of Tecmar . COMDEX FALL 1981, BYTE VOL7 NO.1 PC Magazine Vol1 No.1 PC World Issue1 No.1 PC TechJournal, Vol1 No.1 Test&Meausrement World Vol11 No 10 Decade of Progress Award: Scientific Solutions - LabMaster SEE ALSO
REFERENCES BOOKS ON DATA ACQUISITION ARTICLES ON DATA ACQUISITION Articles about generic data acquisition systems |
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