1、BRITISH STANDARD BS ISO/IEC 8482:1993 Implementation of ISO/IEC8482:1993 Information technology Telecommunications and information exchange between systems Twistedpair multipoint interconnectionsBSISO/IEC8482:1993 This British Standard, having been prepared under the directionof the Information Syst
2、ems Technology Standards Policy Committee, was publishedunder the authority ofthe Standards Board and comesinto effect on 15 August1994 BSI11-1999 The following BSI references relate to the work on this standard: Committee referenceIST/6 Draft for comment92/66586DC ISBN 0 580 23227 1 Committees resp
3、onsible for this British Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical CommitteeIST/6, upon which the following bodies were represented: British Computer Society British Telecommunications plc CCT
4、A (the Government Centre for Information Systems) Digital Equipment Co. Ltd. IBM United Kingdom Ltd. Information Systems Committee of the Universities Funding Council Institution of Electrical Engineers International Computers Limited Logica UK Ltd. Ministry of Defence Rank Xerox Ltd. Swift Project
5、Consortium Amendments issued since publication Amd. No. Date CommentsBSISO/IEC8482:1993 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword iii Text of ISO/IEC8482 1BSISO/IEC8482:1993 ii BSI 11-1999 National foreword This British Standard reproduces ve
6、rbatim ISO/IEC8482:1993 and implements it as the UK national standard. It supersedes BS7248:1990, which is withdrawn. This British Standard is published under the direction of the Information Systems Technology Standards Policy Committee whose Technical Committee IST/6 has the responsibility to: aid
7、 enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. NOTEInternational and European Standa
8、rds, as well as overseas standards, are available from Customer Services, Publications, BSI, Linford Wood, Milton Keynes,MK146LE. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compl
9、iance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theISO/IEC title page, pagesiitoiv, pages1 to16 andaback cover. This standard has been updated (see copyright date) an
10、d may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.ISO/IEC8482:1993(E) ii BSI 11-1999 Contents Page Foreword iii 1 Scope 1 2 Normative reference 1 3 Definitions 1 4 Symbolic representation of an interchange circuit 4 5 Interconnection conf
11、igurations 4 6 Load on the multipoint medium 4 7 Polarities and significant levels 7 8 Generator characteristics 7 9 Receiver characteristics 7 10 Fault condition tests 8 11 Environmental constraints 8 12 Component compatibility 8 Annex A (informative) Guidelines and explanatory notes 12 Annex B (in
12、formative) Guidance on a.c. loading measurement 16 Figure 1 Symbolic representation of interchange circuit 3 Figure 2 Two-wire multipoint configuration 5 Figure 3 Four-wire multipoint configuration 5 Figure 4 Current limit of1,0 UL 6 Figure 5 Input current/voltage measurement 6 Figure 6 UL value det
13、ermination 6 Figure 7 Open circuit voltage measurement 9 Figure 8 Offset voltage measurement 9 Figure 9 Terminated output voltage measurement 9 Figure 10 Rise time measurement 10 Figure 11 Input voltage range 10 Figure 12 Input balance measurement 11 Figure 13 Generator short-circuit test 11 Figure
14、14 Generator contention test 11 Figure A.1 Generator contention with single sourcing generator 14 Figure A.2 Generator contention with multiple sourcing generators 14 Figure B.1 Reflection attenuation measurement 16 Table 1 Receiver differential significant levels 7 Table 2 Compatibility with ITU-T
15、RecommendationV.11 8ISO/IEC8482:1993(E) BSI 11-1999 iii Foreword ISO (the International Organization for Standardization) and IEC (theInternational Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in th
16、e development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-go
17、vernmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IECJTC1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Pub
18、lication as an International Standard requires approval by at least75% of the national bodies casting a vote. International Standard ISO/IEC8482 was prepared by Joint Technical Committee ISO/IECJTC1, Information technology, Subcommittee SC6, Telecommunications and information exchange between system
19、s. This second edition cancels and replaces the first edition (ISO8482:1987), which has been technically revised. Annex A and Annex B of this International Standard are for information only.iv blankISO/IEC8482:1993(E) BSI 11-1999 1 1 Scope 1.1 This International Standard specifies the physical mediu
20、m characteristics for twisted pair multipoint interconnections in either2-wire or4-wire network topology in order to provide for half duplex or duplex data transmission capability, respectively; a binary and bi-directional signal transfer of the interconnected endpoint systems; the electrical and me
21、chanical design of the endpoint system branch cables and the common trunk cable, which may be up to1200m in length; the component measurements of the integrated circuit type generators and receivers within the endpoint systems; the applicable data signalling rate up to12,5Mbit/s. 1.2 The defined ele
22、ctrical component characteristics and measurements are in close conformance with the twisted pair point-to-point characteristics given in ITU-T RecommendationV.11. 1.3 This International Standard does not describe a complete physical interface and has no functional interface characteristics, such as
23、 number of interchange data and control circuits; type, size and pin allocation of the endpoint system and branch trunk cable connectors; data and control signal encoding; time relations between signals on the interchange circuits; mode of synchronous or asynchronous transmission; signal quality for
24、 transmission and reception. 1.4 This International Standard does not specify special environmental conditions, such as galvanic isolation, electromagnetic interference (EMI), radio frequency interference (RFI), and human safety. This may form the subject of a future amendment. 1.5 This Internationa
25、l Standard is primarily a component specification. It is not sufficiently specified for satisfactory interoperation in all possible configurations. It is the responsibility of implementors to ensure that their intended configuration will allow satisfactory interoperation. 1.6 This International Stan
26、dard may be combined with any appropriate set of functional and additional environmental characteristics so as to meet the practical data transmission requirements in the field of local or wide area networks. 2 Normative reference The following ITU-T Recommendation contains certain provisions which,
27、 through reference in this text, constitutes provisions of this International Standard. At the time of publication, the edition indicated was valid. All CCITT Recommendations and International Standards are subject to revision, and parties to agreements based on this International Standard are encou
28、raged to investigate the possibility of applying the most recent edition of the recommendation indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. TheITU-T Secretariat maintains a list of currently valid ITU-T Recommendations. ITU-T RecommendationV.
29、11:1988, Electrical characteristics for balanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications. 3 Definitions For the purposes of this International Standard the following definitions apply: 3.1 balanced interchange circuit
30、an interchange circuit which uses two conductors and the differential mode voltage for transmitting signals 3.2 common mode ejection ratio (CMRR) for balanced interchange circuits, the ratio of an applied common mode voltage, V cmto the resulting transverse voltage V tr(same as the differential mode
31、 voltage) the ratio is normally expressed in decibels as NOTEThe rejection ratio depends upon the circuit termination and should be measured while terminated in normal use. 3.3 common mode voltage one half the vector sum of the voltages between each conductor of a balanced interchange circuit and gr
32、ound or other stated voltage reference NOTEThis voltage may be a transmitted (or received) signal or noise intereference. In the latter case, this voltage is generally not the same as the voltage, which is sometimes referred to as common mode voltage, that may exist (in a common mode) between the en
33、ds of an interchange circuit pair as a result of induction or ground-reference potential difference. CM RR20 V cm V tr - log =ISO/IEC8482:1993(E) 2 BSI 11-1999 3.4 cross-talk loss (near end) for two interchange circuits used for transmission in opposite directions, the ratio, expressed in decibels,
34、of the voltage transmitted on one interchange circuit to the resulting voltage (cross-talk) at the receive end of the other interchange circuit 3.5 cross-talk loss (far end) for two interchange circuits used for transmission in the same direction, the ratio, expressed in decibels, of the voltage tra
35、nsmitted on one interchange circuit to the resulting voltage (cross-talk) at the receive end on the other interchange circuit 3.6 differential mode voltage the vector difference of the voltages between each conductor of a balanced interchange circuit and ground or other stated voltage reference NOTE
36、The differential mode voltage is commonly referred to as the transverse mode voltage. 3.7 environmental conditions those characteristics of the electrical or physical environment, for example EMI, ground potential difference magnetic fields, altitude, temperature,etc., which may affect the operation
37、, with respect to interchange circuits, of a DTE orDCE 3.8 galvanic isolation the existence of a element that is non-conductive with respect to the conductivity of common mode voltage, between the equipment containing a generator and the equipment containing a receiver of an interchange circuit 3.9
38、generator the component of an interchange circuit that is the source of the transmitted signal NOTEThe term generator is used interchangeably with the term driver. 3.10 generator offset voltage the d.c. component of half the vector sum of the voltages between each conductor of a balanced interchange
39、 circuit generator and its signal ground reference NOTEThe d.c. component of half the vector sum of the voltages is the same as the arithmetic mean of the d.c. voltages in the above. 3.11 ground signal the generator/receiver signal voltage reference 3.12 ground earth the voltage reference establishe
40、d by conductive components having a conductive path to earth in the vicinity of the equipment including the generator/receiver NOTEEarth ground is generally synonymous with, and the same as, frame or building ground or protective ground. 3.13 ground potential difference the difference between the si
41、gnal ground potentials of the generator and the receiver of an interchange circuit the potential is the same as the difference in the earth ground potential difference only if the signal ground is connected to earth ground at both the generator and the receiver 3.14 induced noise an interfering volt
42、age that is introduced into an interchange circuit by electromagnetic induction from currents in other conductors for balanced interchange circuits induced voltages generally appear in the common mode 3.15 interchange circuit the circuit, including a generator, a receiver and interconnecting media,
43、that provides for the interchange of signals across an interface, for example DTE/DTE, DTE/DCE, DCE/DCE 3.16 interchange point the point in an interchange circuit at which the specified electrical characteristics of the circuit apply and should be measured NOTEThe interchange point usually defines t
44、he line of demarcation between equipment and is usually the location of an interface connector. 3.17 receiver the component of an interchange circuit that provides for the detection of interchange circuit signals at the receiving equipmentISO/IEC8482:1993(E) BSI 11-1999 3 3.18 rise time the time req
45、uired for a generator output signal voltage to change from a value characteristic of one state to a value characteristic of a second state it is most often specified as the time for the signal voltage to pass between the10% and90% points of the wave form NOTE 1Rise time is normally dependent on the
46、load and is usually specified for a specific test termination. NOTE 2For unbalanced generators, the time for the change from an ON or active state to an OFF or inactive state is sometimes referred to as the “fall time”. 3.19 site conditions the environmental conditions for a given site 3.20 surge vo
47、ltage resistance the ability of an interchange circuit to function normally after being subjected to surges having peak voltages up to some specified value NOTESurge voltage resistance is sometimes referred to as surge immunity. 3.21 surge voltage a transient voltage wave appearing on an interchange
48、 circuit as a result of induction or other phenomenon and having a relatively high value and short duration it is normally acceptable for such surges to cause errors or malfunctions NOTESurges are normally specified with the intent of assuring that equipment will not be damaged by such unusual condi
49、tions. NOTE 1Two interchange points are shown. The output characteristics of the generator, excluding any interconnecting cable, are defined at the “generator interchange point”. The electrical characteristics to which the receiver must respond are defined without the cable termination resistor at the “receiver interchange point”. NOTE 2Points C and C may be interconnected and further connected to protective ground if required by national regulations. Figure 1 Symbolic representation of interchang
