Functional flow block diagram: Difference between revisions

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{{Short description|Flow Diagram}}

[[Image:Functional Flow Block Diagram Format.jpg|thumb|420px|Figure 1: Functional flow block diagram format.<ref name="SEF01">[http://www.dau.mil/pubscats/Pages/sys_eng_fund.aspx ''Systems Engineering Fundamentals.''] {{webarchive|url=https://web.archive.org/web/20110728000913/http://www.dau.mil/pubscats/Pages/sys_eng_fund.aspx |date=2011-07-28 }} Defense Acquisition University Press, 2001</ref>]]

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* ''Function block'': Each function on an FFBD should be separate and be represented by single box (solid line). Each function needs to stand for definite, finite, discrete action to be accomplished by system elements.

* ''Function numbering'': Each level should have a consistent number scheme and provide information concerning function origin. These numbers establish identification and relationships that will carry through all Functional Analysis and Allocation activities and facilitate traceability from lower to top levels.

* ''Functional reference'': Each diagram should contain a reference to other functional diagrams by using a functional title reference (box in brackets).

* ''Flow connection'': Lines connecting functions should only indicate function flow and not a lapse in time or intermediate activity.

* ''Flow direction'': Diagrams should be laid out so that the flow direction is generally from left to right. Arrows are often used to indicate functional flows.

* ''Summing gatesgate'': A circle is used to denote a summing gate and is used when AND/OR is present. AND is used to indicate parallel functions and all conditions must be satisfied to proceed. OR is used to indicate that alternative paths can be satisfied to proceed.

* ''GO and NO-GO pathspath'': “G” and “bar G” are used to denote “go” and “no-go” conditions. These symbols are placed adjacent to lines leaving a particular function to indicate alternative paths.

=== Function symbolism ===