Hierarchical automation structure

The following hierarchy is of importance in the process control to handle all startup and shutdown tasks. First among them is process control level which includes the systems for operation, monitoring, engineering and diagnostics. Then comes process level where server, and processing units are connected to process control level by a terminal bus employing the technique of plant bus to the automation level for data exchange. Next is automation level which consists of programmable logic controllers which provide operating idleness. The direct process interface to the I & C is provided by individual control level. Analog and binary signal transmitters, actuators like motors and electrically actuated valves etc. comes in field level which is connected to the individual control level by copper wires. Fiber optic technology is used in bus system which includes terminal bus and plant bus sections.

Microprocessors and Microcontrollers

Microprocessor is the main component of a data acquisition system. For computer, laptop and server, microprocessor is the key element which is fabricated on a silicone substrate. Intel Corporation manufactured the first microprocessor in the year 1971. Intel came out with first portable embedded system (Intel 4004 microprocessor) which was actually a calculator. A microprocessor can perform arithmetic and logical operations. In 1974, Intel Corporation produced first home computer based on 8-bit Intel 8080. Using the same microprocessor, in 1979 IBM produced a computer which becomes very popular. Intel Corporation continued their work and successfully manufactured superlative microprocessors like 80286, 80386, 80486 and Pentium class of processors.

A microcontroller consists of following components-a microprocessor, memory units and input/output peripherals. All these components are fabricated on a single chip. If software is loaded in the internal memory of the microcontroller, it is called as an embedded chip. Arithmetic and logic unit performs arithmetic and logical operations. One memory unit stores programs. For non-volatile data storage, EEPROM memory is used. For storing variables RAM memory is used. Some special function registers and input-output ports also included in a microcontroller. Circuits for reset, power-up, serial programming, debugging etc. also required here with a serial communication port and an instruction decoder and timing control unit. An analog to digital converter, a few timers and counters are also included in a microcontroller.

4004, 8008, 8080,8086,8087,8088,80286,80386,80486, Pentium, Celeron, Itanium and Pentium M are the different microprocessors manufactured by Intel Corporation. Motorola manufactured some microprocessors like 6800, 68000, 68008, 68030, 68040, PowerPC600, PowerPC601, PowerPC604 etc. Some other manufacturers also developed microprocessors. AMD developed Athlon, Cypress developed CY7C601, DEC developed Alpha, Fujitsu developed MBL8086, Harris developed CS80C286, LSI Logic developed LR30000, Natl. Semi developed NS321016N, SGS-Thomson developed ST6x86, Sun Micro developed SRP1030, Texas Instruments developed TMS390, Toshiba developed TC85R4000 and Zilog developed Z80.