Implementing Datasets

 

 

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A data set (or dataset) is a collection of data. Most commonly a data set corresponds to the contents of a single database table, or a single statistical data matrix, where every column of the table represents a particular variable, and each row corresponds to a given member of the data set in question.

 

The physical structure of each record is nearly the same, and uniform throughout a data set. This is specified in the data control block record format parameter.

 

The fixed-length records eliminate the need for any delimiter byte value for separate records.

 

This means the data may be of any type (binary, floating point or characters) without using a false end-of-record condition.

 

The alternative to a data set is files, which are an unstructured stream of bytes that are favored by Unix, Windows and Mac OS.

 

A data set typically contains a specific type of data such as names, salaries and sales data that are all numerical and fixed-format.

 

Data sets can be organized into a partitioned data set which may hold multiple members that each contain a separate sub-data set.

 

 

 

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Control system actions

 

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The performance of a technical system depends on proper control of its technological functions reacting on varying conditions of its environment.

 

The control system, that fulfills the necessary control actions, should be designed as an integral pan of a technical system. Therefore, the common principles of a technical system design have to be respected during the control system design.

 

An automatic control system (ACS) sustains or improves the functioning of a controlled object. In a number of cases the auxiliary operations for the ACS – starting, stopping, monitoring, adjusting, and so on – can also be automated.

 

An ACS functions mainly as a member of a production or some other complex.

 

In industrial practice, controller designs are performed based on an approximate model of the actual process.

 

It is essential to design a control system which will exhibit a robust performance because the physical systems can vary with operating conditions and time. Gain and phase margins are well known parameters for evaluating the robustness of a control system.

 

An industrial control system (ICS) is essentially responsible for keeping a plant running safely and efficiently. Maintaining control systems is essential to ensuring that plant operations run smoothly. Even when an ICS is connected to older machinery, keep in mind that the control systems require frequent upgrades and run independently of older plant equipment.

 

 

 

 

 

 

 

 

 

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Discrete control (on/off)

 

 

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Sometimes, the control element has only two positions either it is fully closed or fully open.

 

This control element does not operate at any intermediate position, i.e. partly open or partly closed position.

 

The control system made for controlling such elements is known as on-off control theory.

 

In this control system, when process variable changes and crosses certain preset level, the output valve of the system is suddenly fully opened and gives 100 % output .

 

Generally in on-off control system, the output causes change in process variable.

 

A very common example of on-off control theory is fan controlling scheme of transformer cooling system.

 

When transformer runs with such a load, the temperature of the electrical power transformer rises beyond the preset value at which the cooling fans start rotating with their full capacity.

 

 

 

 

 

 

 

 

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Programmable logic controller

 

 

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A programmable logic controller, PLC, or programmable controller is a digital computer used for automation of typically industrial electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many machines, in many industries.

 

Traditionally, PLCs were programmed with a simple type of language called “ladder logic” because they were originally designed to replace relay logic systems.

 

Ladder logic is used to develop software for programmable logic controllers (PLCs) used in industrial control applications.

 

The programmable logic controller is used not only for industrial purpose but also in civil applications such as washing machine, elevators working and traffic signals control.

 

It therefore shares common terms with typical PCs like central processing unit, memory, software and communications.

 

Programmable Logic Controller (PLC) also known as Industrial Computer is the major component in the industrial automation sector.

 

Different types of PLCs from vast number of manufacturers are available in today’s market. Therefore, in the subsequent paragraphs, let us study about PLCs and their types.

 

 

 

 

 

 

 

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