TABLE OF CONTENTS Discrete control used to be considered the opposite of process control, but now the merging of industry needs and the merging of technologies has made the distinction between the two types of control less clear. In fact, it would have made sense to combine the continuous and discrete categories of this book into a single Basic Control category. However the literature is still fairly separate, and this separate categorization still seemed best.
Some of the sensors included in the topic on Discrete Input and Output Devices and General Manufacturing Measurements are continuous, which further confuses the distinction. As with process instrumentation, this topic only scratches the surface of the available types. The topics on Motor and Drive Control and on Motion Control are not "discrete" either, but they fit with PLCs and manufacturing control. Variable Speed Drives are also used in process control.
Motion control is an unknown area to many who work in other areas of automation. However, the tremendous increase in automated equipment is rapidly increasing the range of applications of motion controllers.
Historically, the practice of discrete control evolved quite differently from continuous process control, with very little overlap in technologies and applied principles. Early discrete manufacturing machines were wholly mechanical contrivances, harnessing waterpower through ingenious combinations of drive...
