1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 6 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU$!4!G0G0#/-5.)#!4)/./6%2G0G04(%G0G04%,%0(/.%G0G0.%47/2+%,%#42)#!,G0G0#(!2!#4%2)34)#3G0G0&/23).,%G13#522%.4G0G0).4%2#(!.%G0G0#)2#5)43#/.42/,%$G0G0“9G0G0#/.4!#4G0G0#,/352%)45G134G0G0RecommendationG0G06 (Extract
2、 from the “LUEG0“OOK)NOTES1 ITU-T Recommendation V.31 was published in Fascicle VIII.1 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue
3、Book version and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication ma
4、y be reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VIII.1 - Rec. V.31 1Recommendation V.31Fascicle VIII.1 - Rec. V.31ELECTRICAL CHARACTERISTICS FOR SINGLE-CURRENT INTERCHANGECIRCU
5、ITS CONTROLLED BY CONTACT CLOSURE(Geneva, 1972)1 GeneralIn general, the electrical characteristics specified in this Recommendation apply to interchange circuitsoperating at data signalling rates up to 75 bit/s.Each interchange circuit consists of two conductors (go and return leads) which are elect
6、rically insulated fromeach other and from all other interchange circuits. A common return lead can be assigned to several interchange circuitsof a group.2 Equivalent circuit of interfaceFigure 1/V.31 shows the equivalent interchange circuit, together with the electrical characteristics laid down int
7、his Recommendation. Some electrical characteristics vary depending upon whether the signal receive side is located inthe data circuit-terminating equipment or in the data side is located in the data circuit-terminating equipment or in thedata terminal equipment. This fact is specially referred to be
8、low.3 Signal sourceThe signal source must be isolated from ground or earth irrespective of whether it is located within the datacircuit-terminating equipment or within the data terminal equipment.If the signal receive side is in the data circuit-terminating equipment, the open-contact insulation res
9、istancemeasured from either leg to ground or to any other interchange circuit shall not fall below 5 megohms and thecapacitance measured between the same points shall not exceed 1000 picofarads.Irrespective of the above, the following specifications apply to the signal source.3.1 Internal resistance
10、 of signal source R1, R0The d.c. resistance of the closed contact R1, including the resistance of the interface cable, measured at theinterface (see Figure 1/V.31), should not exceed 10 ohms within the current and voltage ranges of the signal receiveside.The d.c. resistance of the open contact R0inc
11、luding the insulation resistance of the interface cable should notfall below 250 kilohms when measured at the interface (see Figure 1/V.31) within the voltage range of the signal receiveside.3.2 Capacitance of signal source CgThe capacitance of the signal source Cgincluding that of the interface cab
12、le, measured at the interface (seeFigure 1/V.31), should not exceed 2500 picofarads.2 Fascicle VIII.1 - Rec. V.31R1= internal resistance of the signal source in the closed contact conditionR0= internal resistance of the signal source in the open contact conditionCg= capacitance of signal sourceCr= c
13、apacitance of signal receive sideVr= open circuit voltage of signal receive sideIS= current in interchange circuitRr= internal resistance of signal receive sideRE= insulation resistance of signal source if the latter is in the data terminal equipmentCE= ground capacitance of signal source if the lat
14、ter is in the data terminal equipmentFIGURE 1/V.31Equivalent circuit of interface4 Signal receive side4.1 Signal receive side in the data circuit-terminating equipmentThe signal receive side in the data circuit-terminating equipment can be floating or connected to ground at anysingle point.4.1.1 Ope
15、n circuit voltage of the signal receive side VrThe open circuit voltage Vron the signal receive side of the data-circuit terminating equipment, measured at theinterface (see Figure 1/V.31), should not fall below 3 volts and should not exceed 12 volts.4.1.2 Current at interface ISThe current ISsuppli
16、ed by the signal receive side in the data circuit-terminating equipment should not fall below0.1 milliamp and should not exceed 15 milliamps, when measured at the interface (see Figure 1/V.31) in the closedcontact condition, i.e. with an internal resistance of the signal source of R1 10 ohms.Fascicl
17、e VIII.1 - Rec. V.31 3Note - Irrespective of the current IS, in the closed contact conditions, i.e. with an internal resistance of the signalsource of R1 10 ohms, the voltage at the interface should not exceed 150 millivolts, when measured between go andreturn leads.4.1.3 Internal resistance of sign
18、al receive side RrThe internal resistance Rrof the signal receive side of the data circuit-terminating equipment results from thelimits for the open circuit voltage Vrof the signal receive side and the current IS, at the interface, which are specifiedunder 4.1.1 and 4.1.2 above.Even if Rrhas an indu
19、ctive component, the voltage at the interface should not exceed the maximum of 12 voltsspecified under 4.1.1 above.Note - This item is subject to further study.4.1.4 Capacitance of signal receive side CrThe capacitance of Crof the signal receive side in the data circuit-terminating equipment, includ
20、ing thecapacitance of the cable up to the interface (see Figure 1/V.31), is not specified. It is only necessary to ensure that thesignal receive side works satisfactorily, allowing for the capacitance of the signal source Cg.4.2 Signal receive side in the data terminal equipmentThe signal receive si
21、de in the data terminal equipment can be connected to ground at any single point.4.2.1 Open circuit voltage of the signal receive side VrThe open circuit voltage Vrof the signal receive side of the data terminal equipment, measured at the interface(see Figure 1/V.3 1), should not fall below 3 volts
22、and should not exceed 52.8 volts.4.2.2 Current at the interface ISThe current IS, supplied by the signal receive side in the data terminal equipment, should not fall below 10milliamps and not exceed 50 milliamps, when measured at the interface (see Figure 1/V.3 1) in the closed contactcondition, i.e
23、. with an internal resistance of the signal source of R1 10 ohms.4.2.3 Internal resistance of signal receive side RrThe internal resistance Rrof the signal receive side in the data terminal equipment is obtained from the limitsfor the open circuit voltage Vrof the signal receive side and the current
24、 ISat the interface, which are specified under 4.2.1 and 4.2.2 above.Even if Rrhas an inductive component, the voltage at the interface should not exceed the maximum of 52.8volts, specified under 4.2.1.Note - This item is subject to further study.4.2.4 Capacitance of signal receive side CrThe capaci
25、tance of Crof the signal receive side in the data terminal equipment including the capacitance of thecable is not specified. It is only necessary to ensure that the signal receive side works satisfactorily, allowing for thecapacitance of the signal source Cg.4 Fascicle VIII.1 - Rec. V.315 Signal allocationTable 1/V.31 shows allocations of digital signals for data, control and timing circuits.TABLE 1/V.31Closed contactR1 10 Open contactR0 250 kData circuits “1“ condition “0“ conditionControl and timing circuits ON condition OFF condition
