《BS-5070-4-1990.pdf》由会员分享，可在线阅读，更多相关《BS-5070-4-1990.pdf（48页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 5070-4:1990 Engineering diagram drawing practice Part 4: Recommendations for logic diagrams ? Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5070-4:1990 This British Standard, having been prepared under the direction
2、of the General Mechanical Engineering Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 31 October 1990 BSI 15 September 2002 The following BSI references relate to the work on this standard: Committee reference GME/4 Draft for comment 87/7193
3、8 DC ISBN 0 580 18362 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/4 upon which the following bodies were represented: Amalgamated Union of
4、 Engineering Workers (Technical and Supervisory Section) British Engine Group of SMMT British Paper and Board Industry Federation British Railways Board British Standards Society Drawing Office Material Manufacturers and Dealers Association Electricity Supply Industry in England and Wales Electronic
5、 Engineering Association Engineering Equipment and Materials Users Association Gauge and Tool Makers Association Institution of Electrical Engineers Institution of Engineering Designers Institution of Mechanical Engineers Society of British Aerospace Companies Limited Telecommunication Engineering a
6、nd Manufacturing Association United Kingdom Atomic Energy Authority The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Coal Corporation British Shipbuilders British Telecommunications plc GAMBICA (BEAMA Ltd.) Independent Broadcasting
7、 Authority Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5070-4:1990 BSI 15 September 2002 i Contents Page Committees responsibleInside front cover Forewordii Introductio
8、n1 1Scope1 2Definitions1 3Symbols3 4Signal names and characteristics5 5Logic diagrams8 6Logic circuit diagrams12 7Conversion of a logic diagram into a logic circuit diagram30 Appendix A Commonly used abbreviations38 Figure 1 Examples of signal name allocation7 Figure 2 Examples of clock pulses9 Figu
9、re 3 Bit and byte labelling10 Figure 4 Logic states10 Figure 5 Negation11 Figure 6 Examples of negation11 Figure 7 Logic levels13 Figure 8 Indication of logic levels13 Figure 9 Logic convention14 Figure 10 Examples of polarity indication15 Figure 11 AND function16 Figure 12 OR function16 Figure 13 S
10、ymbol duality using negation symbol17 Figure 14 Inversion17 Figure 15 Negation18 Figure 16 Polarity and negation matching24 Figure 17 Connections with inversion24 Figure 18 Connections without inversion25 Figure 19 Connections with negation25 Figure 20 Connections without negation26 Figure 21 Exampl
11、es of supplementary information30 Figure 22 Logic diagram conversion using a combinative element, example 131 Figure 23 Logic diagram conversion using a combinative element, example 233 Figure 24 Diagram conversion35 Table 1 Orientation of symbols3 Table 2 Possible combinations12 Table 3 Examples of
12、 symbol duality using the polarity indicator19 Table 4 Examples of symbol duality using the negation symbol21 Table 5 Diagram indications and relationships27 Table 6 Examples of distributed connections28 Table 7 Commonly used abbreviations38 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:
13、59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5070-4:1990 ii BSI 15 September 2002 Foreword This part of BS 5070 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee. It introduces logic diagrams to form a fourth part of BS 5070. The 1974 editi
14、on of BS 5070, which was withdrawn with the completion of its revision into three parts in 1988, set out recommendations for drawing practice to be followed in preparing engineering diagrams in all fields of engineering with a view to securing uniformity between one drawing office and another in the
15、 same industry. It also aimed to increase uniformity between one field of engineering and another in the basic principles involved and in the designations for different types of diagram. Attention is drawn to BS 5070 being a companion standard to BS 308; the latter covers engineering drawing practic
16、e used in a wide range of engineering disciplines. Commonly, as a diagram can be called a “drawing” and a drawing can be called a “diagram”, it is useful to summarize the difference in the scopes of these standards. BS 308 covers what are commonly accepted to be drawings that define shape, size and
17、form. BS 5070 covers the drawing of diagrams that are normally associated with flow of one sort or another and which relate components (usually indicated by symbols) functionally one to another by the use of lines, but do not depict their shape, size or form; neither do they in general indicate phys
18、ical connections or locations. From experience with the 1974 edition it was decided that for the first revision, whilst bearing in mind the long term aim of uniformity of conventions, there was a need for more comprehensive treatment of the varying requirements of differing industries and for more c
19、areful attention to their presentation. BS 5070 is therefore now revised in parts by which the practice and conventions of several disciplines and industries are collected into three groups. Part 1 covers general principles common to all subsequent parts, which in turn deal particularly with electro
20、technology; control, flow and systems; and logic. BS 5070 gives recommendations for the drawing of engineering diagrams using the symbols given in relevant British Standards. It does not itself originate symbols. The diagrams in this standard contain symbols as they appear in the particular standard
21、s current at the time this publication was prepared. However, although every effort has been made to ensure that correct and current symbols have been used, it has to be recognized that the particular symbols standards are themselves subject to periodic review. It is therefore stressed that the rele
22、vant symbols standards, and not this standard, have to be consulted to obtain definitive symbols. The recommendations of this standard have been established having regard to the requirements of microfilming. Diagrams prepared in accordance with this standard should be suitable for microfilming and r
23、educed-size reproduction techniques. During the course of the first revision particular attention has been paid to developments in computer aided machine draughting and it has been established that such machines are currently capable of complying with this standard. Any minor exceptions due to the l
24、imitations of a particular system would not be expected to prejudice the understanding of a diagram otherwise claimed to comply with this standard. It is recognized that though this standard is published in a number of parts, there may be instances when certain recommendations and descriptions are r
25、epeated. This has been kept to a minimum and it is hoped that all the needs of any specialized engineering discipline are contained in the part of BS 5070 that deals with those specific needs. This part of BS 5070 deals with logic diagram drawing and follows the recommendations being formulated inte
26、rnationally through the International Electrotechnical Commission (IEC). Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5070-4:1990 BSI 15 September 2002 iii Part 1 deals with general principles of diagram drawing and is the base documen
27、t. Part 2 deals with all forms of diagrams in electrical, electronics and telecommunications engineering. Part 3 deals with a variety of non-electrical diagrams including those concerned with control and flow; transfer of materials (both solids and fluids, i.e. liquids, vapours and gases); and energ
28、y transfer (hydraulic, pneumatic and mechanical). Compliance with a British Standard does not of itself confer immunity from legal obligations. Notes on the presentation of this standard NOTE 1The figures illustrating the text in this standard are independent and each is selected solely for its simp
29、licity and clarity to illustrate only the text to which it relates. They are not the only possible examples and they are not intended as design examples or to be fully working diagrams, but otherwise are drawn according to the basic recommendations of this standard. NOTE 2Numerical values of compone
30、nts given in the figures throughout are arbitrarily chosen to assist in illustrating the point under consideration; they are typical and are not given as recommendations. NOTE 3In the illustrations to this standard, a convention is adopted of using capital letters for notes that would appear as part
31、 of the drawing and lower case letters are used for notes explaining the point under consideration in relation to the text. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 40, an inside back cover and a back cover. The BSI copyright notice dis
32、played in this document indicates when the document was last issued. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5070-
33、4:1990 BSI 15 September 2002 1 Introduction A symbol for a binary logic element may represent either a concept, i.e. a theoretical or an ideal item, or a real hardware item. In programmable equipment the symbols are used to represent programme elements in modules. Binary logic is concerned with vari
34、ables, each of which may take up one of two states. These states may be described by terms such as ON and OFF, YES and NO, TRUE and FALSE or more usually as the logic 1-state and the logic 0-state. The symbols for logic functions in BS 3939-12 represent the relationship between the inputs and output
35、s in terms of logic states. They may therefore be used in diagrams representing abstract logic designs and no difficulties of interpretation should arise. At this stage no knowledge is needed as to what type of device (e.g. electric, fluidic) will eventually be used to implement the design. As soon
36、as hardware items are selected to carry out the desired logic functions it becomes necessary to decide on the physical quantities that will be used to represent the logic states. With electrical devices it is usual to select electrical potential as the physical quantity and to assign values to repre
37、sent the logic states. However, for other possibilities see 6.3. Absolute figures are not normally used and the values are merely identified as more positive or less positive. These two values are known as logic levels. This part of BS 5070 uses the symbols 0 and 1 to identify the two logic states o
38、f a binary variable. These states are referred to as the 0-state and the 1-state. A binary variable may be related to any physical quantity for which two distinct ranges can be defined. In this standard, these distinct ranges are referred to as logic levels and are denoted H and L. H is used to deno
39、te the logic level with the more positive algebraic value, and L is used to denote the logic level with the less positive algebraic value. In cases where the logic levels are equated with other qualities of physical quantity (e.g. positive or negative pulses, presence or absence of a pulse) H and L
40、may be used to represent these qualities or may be replaced by more suitable designations. 1 Scope This part of BS 5070 gives recommendations for the practice to be followed in preparing logic diagrams and the application of binary logic symbols for such diagrams. It should be read in conjunction wi
41、th Part 1 and Part 2. Analogue and hybrid techniques have not been considered. This part is applicable to those forms of integrated circuit design in which the basic logic circuit elements are predefined cells which are laid out and interconnected in a manner similar to packages on a printed circuit
42、 board. These integrated circuits are known as uncommitted logic arrays, gate arrays, or standard cell arrays. NOTE 1The logic circuit diagrams will not contain internal pin numbers, but in all other respects should have the characteristics of the diagrams shown as examples in this standard. NOTE 2T
43、he symbols and descriptions have been prepared with a view to electrical applications but they are equally applicable to other, non-electrical systems such as pneumatic, hydraulic or mechanical. NOTE 3The titles of the publications referred to in this standard are listed on the inside back cover. 2
44、Definitions For the purposes of this part of BS 5070 the following definitions apply. 2.1 logic diagram a diagram that uses symbols for binary logic elements to depict the overall function of a system in terms of logic stages and is not necessarily related to physical implementation 2.2 logic circui
45、t diagram a diagram that shows the practical implementation of a logic diagram. This diagram will also show components that are not logic stages but are necessary to make the system work NOTEWhen the logic diagram is to be implemented in a practical form, a more detailed diagram has to be prepared t
46、hat shows symbols for the actual gates used (see also clause 7). Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 09:59:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5070-4:1990 2 BSI 15 September 2002 2.3 stage an element or group of elements that act(s) upon one or more incoming signals t
47、o develop one or more output signals, the two types of which are: a) logic stage. A stage that performs a logic function e.g. AND, OR, NEGATION, delay or storage b) non-logic stage. A stage that performs a non-logic function e.g. amplification, pulse regeneration, adjustment of levels, impedance tra
48、nsformations, etc 2.4 positive logic convention the representation of the 1-state and the 0-state by the High (H) and Low (L) levels respectively 2.5 negative logic convention the representation of the 1-state and the 0-state by the Low (L) and High (H) levels respectively 2.6 polarity indicator con
49、vention the designation of the internal state produced by the external level of an input, or producing the external level of an output, by the presence or absence of the polarity indicator symbol 2.7 logic state one of two possible abstract states that may be taken on by a logic (binary) variable, the two types of which are: a) 0-state. The logic state represented by the binary symbol 0 denoting a false logic condition b) 1-state. The logic st