1、BRITISH STANDARD BS 5070-4:1990 Engineering diagram drawing practice Part 4: Recommendations for logic diagrams BS 5070-4:1990 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standards Policy Committee, was published under the authority of the Bo
2、ard 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 87/71938 DC ISBN 0 580 18362 9 Committees responsible for this British Standard The preparation of this British Stan
3、dard 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 Engineering Workers (Technical and Supervisory Section) British Engine Group of SMMT British Paper and Board
4、 Industry Federation British Railways Board British Standards Society Drawing Office Material Manufacturers and Dealers Association Electricity Supply Industry in England and Wales Electronic Engineering Association Engineering Equipment and Materials Users Association Gauge and Tool Makers Associat
5、ion Institution of Electrical Engineers Institution of Engineering Designers Institution of Mechanical Engineers Society of British Aerospace Companies Limited Telecommunication Engineering and Manufacturing Association United Kingdom Atomic Energy Authority The following bodies were also represente
6、d in the drafting of the standard, through subcommittees and panels: British Coal Corporation British Shipbuilders British Telecommunications plc GAMBICA (BEAMA Ltd.) Independent Broadcasting Authority Amendments issued since publication Amd. No. Date of issue CommentsBS 5070-4:1990 BSI 15 September
7、 2002 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1S c o p e 1 2 Definitions 1 3S y m b o l s 3 4 Signal names and characteristics 5 5L o g i c d i a g r a m s 8 6 Logic circuit diagrams 12 7 Conversion of a logic diagram into a logic circuit diagram 30 Appen
8、dix A Commonly used abbreviations 38 Figure 1 Examples of signal name allocation 7 Figure 2 Examples of clock pulses 9 Figure 3 Bit and byte labelling 10 Figure 4 Logic states 10 Figure 5 Negation 11 Figure 6 Examples of negation 11 Figure 7 Logic levels 13 Figure 8 Indication of logic levels 13 Fig
9、ure 9 Logic convention 14 Figure 10 Examples of polarity indication 15 Figure 11 AND function 16 Figure 12 OR function 16 Figure 13 Symbol duality using negation symbol 17 Figure 14 Inversion 17 Figure 15 Negation 18 Figure 16 Polarity and negation matching 24 Figure 17 Connections with inversion 24
10、 Figure 18 Connections without inversion 25 Figure 19 Connections with negation 25 Figure 20 Connections without negation 26 Figure 21 Examples of supplementary information 30 Figure 22 Logic diagram conversion using a combinative element, example 1 31 Figure 23 Logic diagram conversion using a comb
11、inative element, example 2 33 Figure 24 Diagram conversion 35 Table 1 Orientation of symbols 3 Table 2 Possible combinations 12 Table 3 Examples of symbol duality using the polarity indicator 19 Table 4 Examples of symbol duality using the negation symbol 21 Table 5 Diagram indications and relations
12、hips 27 Table 6 Examples of distributed connections 28 Table 7 Commonly used abbreviations 38BS 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 f
13、orm a fourth part of BS 5070. The 1974 edition 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 b
14、etween one drawing office and another in the 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; t
15、he latter covers engineering drawing practice 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
16、 to be drawings that define shape, size and 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 fo
17、rm; neither do they in general indicate physical 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 require
18、ments of differing industries and for more careful 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,
19、which in turn deal particularly with electrotechnology; 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 symbo
20、ls as they appear in the particular standards 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 re
21、view. It is therefore stressed that the relevant 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 standa
22、rd should be suitable for microfilming and reduced-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
23、 standard. Any minor exceptions due to the limitations 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 ce
24、rtain recommendations and descriptions are repeated. 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 follo
25、ws the recommendations being formulated internationally through the International Electrotechnical Commission (IEC).BS 5070-4:1990 BSI 15 September 2002 iii Part 1 deals with general principles of diagram drawing and is the base document. Part 2 deals with all forms of diagrams in electrical, electr
26、onics 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 energy transfer (hydraulic, pneumatic and mechanical). Compliance wit
27、h a British Standard does not of itself confer immunity from legal obligations. Notes on the presentation of this standard NOTE 1 The figures illustrating the text in this standard are independent and each is selected solely for its simplicity and clarity to illustrate only the text to which it rela
28、tes. 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 2 Numerical values of components given in the figures throughout are arbitrarily chosen to
29、assist in illustrating the point under consideration; they are typical and are not given as recommendations. NOTE 3 In the illustrations to this standard, a convention is adopted of using capital letters for notes that would appear as part of the drawing and lower case letters are used for notes exp
30、laining 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 displayed in this document indicates when the document was last
31、issued.iv blankBS 5070-4:1990 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
32、 is concerned with variables, 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 betwee
33、n the inputs and outputs 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 impleme
34、nt the design. As soon 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
35、 assign values to represent 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
36、 the two logic states of 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 a
37、nd L. H is used to denote 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 absen
38、ce of a pulse) H and L 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
39、 read in conjunction with 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 packag
40、es on a printed circuit board. These integrated circuits are known as uncommitted logic arrays, gate arrays, or standard cell arrays. NOTE 1 The logic circuit diagrams will not contain internal pin numbers, but in all other respects should have the characteristics of the diagrams shown as examples i
41、n this standard. NOTE 2 The 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 3 The titles of the publications referred to in this standard are listed on
42、 the inside back cover. 2 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 imple
43、mentation 2.2 logic circuit 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 NOTE When the logic diagram is to be implemented in a practical form, a more detailed d
44、iagram has to be prepared that shows symbols for the actual gates used (see also clause 7).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 to develop one or more output signals, the two types of which are: a) logic stage.
45、 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 transformations, etc 2.4 positive logic convention the representation of the 1-state
46、 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 convention the designation of the internal state produced by the external level of a
47、n 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
48、symbol 0 denoting a false logic condition b) 1-state. The logic state represented by the binary symbol 1 denoting a true logic condition 2.8 internal logic state the logic state assumed to exist inside an element symbol outline at an input or output 2.9 external logic state the logic state assumed t
49、o exist outside an element symbol outline: a) on an input line prior to any external qualifying symbol of that input, or b) on an output line beyond any external qualifying symbol at that output 2.10 logic level any level within one of two non-overlapping ranges of value of a physical quantity used to represent the logic state, the two ranges of which are: a) high (H) level. A level within the more positive (less negative) of the two ranges of logi
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