There are many situations where data is required in digital form from a number of points simultaneously, either for the record or as a prerequisite to control. Not so very long ago, information was usually presented in analogue form by the position of a pointer on a dial, and an operator had to read a number of dials in order to control a machine or a process. As systems became faster and more complex, the operator’s task became more difficult and, in some systems, impossible. Similarly, if a permanent record was required, a multichannel chart recorder was used. Even though most sensors still present their output as a voltage or current analogue of the quantity being measured (the measurand) it is now usual to convert the incoming analogue signal into digital form, i.e. into a series of numbers known as data. This change has been caused by the cost of employing an operator increasing at the same time as the cost of digital electronics and computers have been decreasing. In addition, a computer can read more information and act on it more quickly, to achieve real-time control.
KeywordsData Acquisition System Digital Form Random Access Memory Digital Converter Signal Conditioning
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