数据采集外文资料翻译.docVIP

外文资料原文 Data Acquisition Powerful mini and mainframe computers are used to combine the data acquisition with other functions such an comparisons between the actual output and the desirable output values and to then decide on the control action which must be taken to ensure that the output variables lie within pre-set limits, The computing power required will depend upon the type of process control system implemented. Software requirements for carrying out proportional, ratio or three term control of process variables are relatively trivial, and microcomputers can be used to implement such process control systems. It would not be possible to use many of the currently available microcomputers for the implementation of high speed adaptive control systems which require the use of suitable process models and considerable on-line manipulation of data. Microcomputer based data loggers are used to carry out intermediate functions such as data acquisition at comparatively low speeds, simple mathematical manipulations of raw data and some forms of data reduction. The first generation of data loggers, without any programmable computing facilities, were used simply for slow speed data acquisition from up to one hundred channels. All the acquired data could be punched out on paper type or printed for subsequent analysis. Such hardwired data loggers are being replaced by the new generation of data loggers are being replaced by the new generation of data loggers which incorporate microcomputers and can be programmed by the user. They offer an extremely good method of collecting the process data, using standardized interfaces and subsequently performing the necessary manipulations to provide the information of interest to the process operator. the data acquired can be analyzed to establish correlations, if any, between process variables and to develop mathematical models necessary for adaptive and optimal process control. If the analog data must be transmitted over any distance, dif