Digital computation and intelligent devices

This chapter discusses about the principles of digital computation and its application in measurement systems. Digital computers have been used in conjunction with measurement systems for many years in the typical control system scenario, where a computer uses data on process variables supplied by a measurement system to compute a control signal that is then applied to an actuator to modify some aspect of the controlled process. The primary function of a digital computer is the manipulation of data. The three elements that are essential to the fulfillment of this task are the central processing unit, the memory, and the input-output interface, The distinction between the terms “microcomputer,” “minicomputer,” and “mainframe computer” is a very arbitrary division made according to relative computer power. The term “intelligent device” is used to describe a package containing either a complete measurement system, or else a component within a measurement system, which incorporates a digital processor. The first intelligent instrument was launched over 20 years ago; although high prices when such devices first became available meant that their use within measurement systems grew very slowly initially. A smart sensor is a sensor with local processing power that enables it to react to local conditions without having to refer back to a central controller. In concept, a smart transmitter is almost identical to the intelligent instruments described earlier. Many of the features of smart transmitters are common with those of smart sensors, and the comments made earlier about smart sensors therefore apply equally.