Block diagram

From Wikipedia, the free encyclopedia

This article may require cleanup to meet Wikipedia's quality standards.
Please improve this article if you can. (July 2006)

An example block diagram, showing the Microsoft Windows 2000 operating system architecture.

A high level block diagram of a bicycle light system (electrical engineering)

A low level block diagram of a bicycle light system (electrical engineering)

A schematic diagram of a bicycle light system (electrical engineering)

A schematic diagram of a bicycle light system mixed with a block diagram to show the relationship between the two (electrical engineering)

A block diagram is a pictorial model of a process or system. 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 diagram 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. For example, a block diagram of a radio 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, 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. (ARRL 2006, p. 26.7) ^[1]

Block diagrams rely on the principle of the black box 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. (Nilsson 1986, p. 43) (Hayes 1988, p. 89) ^[2] ^[3]

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. (Hayes 1988, p. 92)

Geometric shapes (e.g. rectangles, circles etc.) 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.

[edit] See also

[edit] References

^ ARRL, ARRL Handbook for Radio Communications (Eighty-Third ed.), Amateur Radio Relay League (ARRL), ISBN 0-87259-948-5 .
^ Nilsson, James W., Electric Circuits (Second ed.), Addison Wesley Publishing Company (published October 1986), ISBN 0-201-12695-8 .
^ Hayes, John P. (1988), Computer Architecture and Organization (Second ed.), McGraw Hill Publishing Company, ISBN 0-07-027366-9 .