- Block diagram
Block diagram is a
diagramof a system, in which the principal parts or functions are represented by blocks connected by lines, that show the relationships of the blocks. [http://pascal.computer.org/sev_display/index.action SEVOCAB: Software and Systems Engineering Vocabulary] . Term: "block diagram". retrieved 31 July 2008.] They are heavily used in the engineering world in hardware design, software design, and process flow diagrams.
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 diagramand layout diagramused 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.
As an example, a block diagram of a
radiois 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, 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. [Citation | author=
American Radio Relay League(ARRL) | title =ARRL Handbook for Radio Communications | edition =Eighty-Third | publisher =Amateur Radio Relay League |isbn=0872599485]
Block diagrams rely on the principle of the
black boxwhere 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. [Citation | last =Nilsson | first =James W. | publication-date =October 1986 | date =1986 | title =Electric Circuits
edition =Second | publisher =Addison Wesley Publishing Company |isbn =0201126958 ] Citation | last =Hayes | first =John P. |date=1988 | title =Computer Architecture and Organization | edition =Second | publisher =McGraw Hill Publishing Company |pages=89-92 | isbn =0070273669]
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. 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.
Functional flow block diagram
* [http://web2.concordia.ca/Quality/tools/3blockdiagram.pdf Concordia Block Diagram]
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