Data manipulation instructions enable the PLCs to take on additional characteristics that are beyond the conventional relay equivalent instruction. It allows the movement, manipulation or storage of data in either single or multi-word groups from one data memory area of the PLC to another. Therefore, data manipulation can be divided into many categories Data transfer
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The “brain” of the system which has three sub-parts. Central Processing Unit (CPU) (i) Microprocessor: Microprocessor caries out mathematic and logical operations. (ii) Memory: The area of the CPU in which data and information is stored and retrieved. It holds the system software and user program. (iii) Power supply: The electrical supply that converts Alternating
Central Processing Unit (CPU) – Input and Output Modules Read More »
At Common Law, the Crown could not be sued in tort’ either for wrong actually authorized by it or committed by its servants, in the course of their employment. Moreover, no action could lie against the head of the department or other superior officials for the acts of their subordinates for relationship between them was
Vicarious Liability of the State – Position in England Read More »
Press is a metal forming machine tool used to shape or cut metal by applying force. Press working may be defined as a chipless manufacturing process by which various components are made from sheet metal. Many components in our day to day life are made by press working operations. Press working is mainly useful for
Press Working Terminology and Elements of Cutting Dies Read More »
Conventional machines are controlled by human operators. The machine control involves feed movements, positioning and sequencing etc. Due to repeated operations and environmental influences, there is an uncertainty in the quality and reliability of parts produced. A numerically controlled machines tool is the one that is controlled by numbers. The instructions are coded as a
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Sheet metal parts are characterized by its complicated shapes. Computer aids for Sheet metal forming operations are conducted close to the failure limit and therefore, small changes in conditions and properties of material can cause large changes in failure rates. Before deciding the forming process and tools, the tool designer has to determine whether the
Computer Aids for Sheet Metal Forming Analysis Read More »
NC machine tool by means of prepared program, which consists of blocks, or series of numbers, is know as numerical control (NC). In manufacturing of more complicated parts, the system has to calculate automatically additional data points, which is done by means of an interpolator The capability of changing the programs provides the advantage of
NC Machine Tool Fixtures – Design Difficulties Read More »
We use arrays structures to describe the format of a number of related variables. For example, in analyzing the marks obtained by a class of students, we may use a template to describe student name and marks obtained in various subjects and then declare all the students as structure variables. In such cases, we may
Arrays Structures and Unions in C, Structures and Functions Read More »
Variables in C differ in behavior from those in most other languages. For example, in a BASIC program, a variable retains its value throughout the program. It is not always the case in C. It all depends on the ‘storage’ class a variable may assume. In C not only do all variables have a data
Variables in C – The Scope, Visibility and lifetime of Variables Read More »
Types of fixtures are used to hold the workpiece during machining operations. The name is derived from the fact that a fixture is always fixed or fastened to a machine in the fixed position. It does not contain arrangements for guiding the tool. The use of fixture becomes essential when the components to be produced
Types of Fixtures – Lathe Fixtures or Turning Fixtures Read More »