Microprocessor based control system range from a small programmable controller to a microprocessor used to control an entire fractionating column in an oil refinery.
A few of the micro controller based applications have been discussed here. Microprocessors are now rapidly replacing mechanical cam-operated controllers and being used in general to carry out functions. The following examples illustrate the basic aspects of microprocessor-based system that can be used to control focusing and exposure, sequence of washing cycle, managing the ignition and fueling requirements in automatic cameras, automatic washing machine and engine management respectively.
Automatic camera
Modern cameras are fully automatic including focusing and exposure. Fig. 1.14 illustrates the basic elements of the control system for an automatic camera.
in improved reliability, maintainability, reduction is size of the control system and manufacturing cost. Some of the application areas of microprocessor and micro controller-based system include
a. automobile engines
b. industrial automations
c. web-based process monitoring and control application etc.
Data Ocquisition System converts the analog signal from various sensors to digital signals that can be processed by a microprocessor. A keyboard and display in the system allow the user to enter set point values which are stored in the memory and the feed back of the current values are the process variable are read into the memory. Relays, DAS, solenoid valves and other actuators are used to control the process variables using the program. Fig. 1.13 shows a block diagram of a microprocessor basec ontrol system.