Block diagram is a diagram A diagram is a two-dimensional geometric symbolic representation of information according to some visualization technique. Sometimes, the technique uses a three-dimensional visualization which is then projected onto the two-dimensional surface. The word graph is sometimes used as a synonym for diagram of a system System is a set of interacting or interdependent entities forming an integrated whole, in which the principal parts or functions are represented by blocks connected by lines, that show the relationships of the blocks.[1] They are heavily used in the engineering world in hardware design CPU design is the design engineering task of creating a central processing unit , a component of computer hardware. It is a subfield of electronics engineering and computer engineering, software design Software design is a process of problem-solving and planning for a software solution. After the purpose and specifications of software are determined, software developers will design or employ designers to develop a plan for a solution. It includes low-level component and algorithm implementation issues as well as the architectural view, and process flow diagrams A PFD can be computer generated from process simulators , CAD packages, or flow chart software using a library of chemical engineering symbols. Rules and symbols are available from standardization organizations such as DIN, ISO or ANSI. Often PFDs are produced on large sheets of paper.
The block diagram is typically used for a higher level, less detailed description aimed more at understanding the overall concepts and less at understanding the details of implementation. Contrast this with the schematic diagram A schematic is a diagram that represents the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the information the schematic is intended to convey, and may add unrealistic elements that aid comprehension. For example, a subway map intended for riders and layout diagram used in the electrical engineering world, where the schematic diagram shows the details of each electrical component and the layout diagram shows the details of physical construction. Because block diagrams are a visual language for describing actions in a complex system, it is possible to formalize them into a specialized programmable logic controller (PLC) programming language. A Function block diagram is one of five programming languages defined in part 3 of the IEC 61131 (see IEC 61131-3) standard. Since this is a real, bona fide computer programming language, it is highly formalized (see formal system In formal logic, a formal system consists of a formal language and a set of inference rules, used to derive (to conclude) one expression from one or more other expressions (premises) antecedently supposed (axioms) or derived (theorems). The axioms and rules may be called a deductive apparatus. A formal system may be formulated and studied for its) with strict rules for how diagrams are to be built. Directed lines are used to connect input variables to function inputs, function outputs to output variables, and function outputs to inputs of other functions. These blocks portray mathematical or logical operations that occur in time sequence. They do not represent the physical entities, such as processors or relays, that perform those operations. Each block is therefore a black box In science and engineering, a black box is a device, system or object which can be viewed solely in terms of its input, output and transfer characteristics without any knowledge of its internal workings, that is, its implementation is "opaque" . Almost anything might be referred to as a black box: a transistor, an algorithm, or the human. The rules require the logical sequence to go from left to right and top to bottom.
Usage examples
As an example, a block diagram of a radio Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing some property of the radiated waves, such as is not expected to show each and every wire and dial and switch, but the schematic diagram is. The schematic diagram of a radio does not show the width of each wire in the printed circuit board A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring board. A PCB populated with electronic components is a, but the layout diagram does.
To make an analogy to the map making world, a block diagram is similar to a highway map of an entire nation. The major cities (functions) are listed but the minor county roads and city streets are not. When troubleshooting, this high level map is useful in narrowing down and isolating where a problem or fault is.[2]
Block diagrams rely on the principle of the black box In science and engineering, a black box is a device, system or object which can be viewed solely in terms of its input, output and transfer characteristics without any knowledge of its internal workings, that is, its implementation is "opaque" . Almost anything might be referred to as a black box: a transistor, an algorithm, or the human where the contents are hidden from view either to avoid being distracted by the details or because the details are not known. We know what goes in, we know what goes out, but we can't see how the box does its work.[3][4]
In electrical engineering, a design will often begin as a very high level block diagram, becoming more and more detailed block diagrams as the design progresses, finally ending in block diagrams detailed enough that each individual block can be easily implemented (at which point the block diagram is also a schematic diagram). This is known as top down design.[4] Geometric shapes are often used in the diagram to aid interpretation and clarify meaning of the process or model. The geometric shapes are connected by lines to indicate association and direction/order of traversal. Each engineering discipline has their own meaning for each shape.
See also
- Black box In science and engineering, a black box is a device, system or object which can be viewed solely in terms of its input, output and transfer characteristics without any knowledge of its internal workings, that is, its implementation is "opaque" . Almost anything might be referred to as a black box: a transistor, an algorithm, or the human
- Bond graph
- Data flow diagram A data-flow diagram is a graphical representation of the "flow" of data through an information system. DFDs can also be used for the visualization of data processing (structured design)
- Functional flow block diagram The FFBD notation was developed in the 1950s, and is widely used in classical systems engineering. FFBDs are one of the classic business process modeling methodologies, along with flow charts, data flow diagrams, control flow diagrams, Gantt charts, PERT diagrams, and IDEF
- One-line diagram
- Schematic diagram A schematic is a diagram that represents the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the information the schematic is intended to convey, and may add unrealistic elements that aid comprehension. For example, a subway map intended for riders
- Signal-flow graph
References
- ^ SEVOCAB: Software and Systems Engineering Vocabulary. Term: block diagram. retrieved 31 July 2008.
- ^ American Radio Relay League The American Radio Relay League is the largest membership association of amateur radio enthusiasts in the USA. ARRL is a non-profit organization, and was founded in May 1914 by Hiram Percy Maxim of Hartford, Connecticut. The ARRL represents the interests of amateur radio operators before federal regulatory bodies, provides technical advice and (ARRL) (2005), ARRL Handbook for Radio Communications (Eighty-Third ed.), Amateur Radio Relay League, ISBN The International Standard Book Number is a unique numeric commercial book identifier based upon the 9-digit Standard Book Numbering (SBN) code created by Gordon Foster, now Emeritus Professor of Statistics at Trinity College, Dublin, for the booksellers and stationers W.H. Smith and others in 1966 0872599485
- ^ Nilsson, James W. (1986), Electric Circuits (Second ed.), Addison Wesley Publishing Company (published October 1986), ISBN The International Standard Book Number is a unique numeric commercial book identifier based upon the 9-digit Standard Book Numbering (SBN) code created by Gordon Foster, now Emeritus Professor of Statistics at Trinity College, Dublin, for the booksellers and stationers W.H. Smith and others in 1966 0201126958
- ^ a b Hayes, John P. (1988), Computer Architecture and Organization (Second ed.), McGraw Hill Publishing Company, pp. 89–92, ISBN The International Standard Book Number is a unique numeric commercial book identifier based upon the 9-digit Standard Book Numbering (SBN) code created by Gordon Foster, now Emeritus Professor of Statistics at Trinity College, Dublin, for the booksellers and stationers W.H. Smith and others in 1966 0070273669
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hu, 17 Jun 2010 13:25:13 GM
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