Control system microprocessors

Chemical and physical property measnrements Ionizing radiation levels Nonionizing radiation levels Overriding antomatic controls Large-scale compnter control systems Microprocessor control systems Programmable logic devices Internet-enabled controls, monitoring, and health Software controls... 

Logic elements for high-integrity instrumentation and control systems -microprocessors, analog systems, gated arrays, and others. 

The electronic block, which includes block of the analysis and registration and control system engines, and block of the source-receiver of acoustic oscillations are universal for any installations of this type. As the source-receiver of acoustic oscillations the ultrasonic flow detector is usually use. It s, as a rule, the serial devices for example y/f2-12. The electronic block contains the microprocessor device or PC, device of the power supply and management of engines... 

Since 1970, new analytical techniques, eg, ion chromatography, have been developed, and others, eg, atomic absorption and emission, have been improved (1—5). Detection limits for many chemicals have been dramatically lowered. Many wet chemical methods have been automated and are controlled by microprocessors which allow greater data output in a shorter time. Perhaps the best known continuous-flow analy2er for water analysis is the Autoanaly2er system manufactured by Technicon Instmments Corp. (Tarrytown, N.Y.) (6). Isolation of samples is maintained by pumping air bubbles into the flow line. Recently, flow-injection analysis has also become popular, and a theoretical comparison of it with the segmented flow analy2er has been made (7—9). 

With the advent of the microprocessor, digital technology began to be used for data collection, feedback control, and aU other information processing requirements in production facUities. Such systems must acquire data from a variety of measurement devices, and control systems must drive final actuators. 

Microprocessor technology permitted these technical issues to be addressed in a cost-effec tive manner. In the mid-1970s, a process control architecture referred to as a distributed control system (DCS) was introduced and almost instantly became a commercial success. A DCS consists of some number of microprocessor-based nodes that are interconnec ted by a digital communications network, often called a data highway. The key features of this architecture are as follows ... 

Conveyor installations maybe permanent or a combination of permanent and portable. The latter kind is often mounted on a bulk-deliveiy vehicle, which permits fast unloading into the customers silo by the carrier without effort or equipment from the customer. Controls range from simple motor starters and hand-connected hoses to sophisticated, microprocessor-elec tropueumatic control systems. 

With this technology it is now possible to achieve extremely accurate speed control of the order of 0.01 % to 0.001 %. To achieve such high accuracy in speed control, closed-loop feedback control systems and microprocessor-based control logistics can be introduced into the inverter control scheme to sense, monitor and control the variable parameters of the motor to very precise limits. 

Very accurate controls through microprocessor-based closed-loop feedback control systems... 

Moderate to precise controls as for a.c. drives possible with the use of microprocessor-based control systems... 

Microprocessor-based control systems are being increasingly used in place of traditional instrumentation. Some accidents that have occurred on these systems are described in Chapter 20. 

Many air conditioning systems use simple thermostats to cycle equipment however, more sophisticated control systems employing electronics and microprocessors can reduce energy consumption. 

Manufacturers now offer as standard microprocessor-based control systems as part of their gas turbine generator set. The set can therefore be controlled and monitored from panels adjacent to the machine or, if required, remotely from a central control room. In combined-cycle installations, the system would be linked into the... 

An extruder for a polymer was controlled by a microprocessor based data acquisition and control system. The CAMILE system (Control And Monitoring Interface for Laboratory Experiments) connects the sensors and control elements of the extruder to a host MS-DOS computer. While a variety of variables are measured and controlled, this paper will consider only temperature control. 

Multistep batch processes are amenable to microprocessor-based control systems. Porte et al. (1982) have shown that the seven-step process for making (1-ethyl-2-pyrrolidinyl) (2-... 

The arrival of integrated circuits with very good performance/price ratios and relatively low-cost microprocessors and memories has had a profound influence on many areas of technical endeavour. Also in the measurement and control field, modem electronic circuits were introduced on a large scale leading to very sophisticated systems and novel solutions. However, in these measurement and control systems, quite often sensors and actuators were applied that were conceived many decades ago. Consequently, it became necessary to improve these devices in such a way that their performance/price ratios would approach that of modem electronic circuits. 

A detailed discussion of the application of digital computers and microprocessors in process control is beyond the scope of this volume. The use of computers and microprocessor based distributed control systems for the control of chemical process is covered by Kalani (1988). 

KALANI, G. (1988) Microprocessor Based Distributed Control Systems (Prentice Hall). 

Parallel to these customer-driven requirements, we have also seen a change in technology. Electronic control systems and microprocessors in particular have become more powerful, while prices have been falling. 

Distributed Control System (DCS) - A generic, microprocessor based, regulatory system for managing a system, process or facility. 

Today most new control systems use distributed control hardware microprocessors that serve several control loops simultaneously. Information is displayed on CRTs (cathode ray tubes). Most signals are transmitted in analog electronic form (usually current signals). 

Digital computers are used in process control systems on a time-shared basis. A single digital computer (or microprocessor) services a number of control... 

Fig. 11.8. The essential elements of a computer-controlled STM. The feedback electronics is replaced by a single-CPU computer. A Motorola 68020 microprocessor and a 68881 math coprocessor are used to perform the feedback control. A commercial VME crate is applied. The versatility of the software-controlled system facilitates the optimization of the transient response of the STM. (Reproduced from Piner and Reifenberger, 1989, with permission.)...

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