1、INTERNATIONAL STANDARD ISO/IEC 8877 Second edition 1992-1 l-l 5 Information technology - Telecommunications and information exchange between systems - Interface connector and contact assignments for ISDN Basic Access Interface located at reference points S and T Technologies de Iinformation - T - Th
2、e plug at each end of the cord shall be an 8-pole 2 ISO/IEC 8877: 1992(E) plug as specified in clause 4 and figures 1, 3, and 4, but with physical contacts fitted only in contact positions 3, 4, 5, and 6. Contacts shall not be fitted in positions 1, 2, 7 and 8. - contact assignments for conductors a
3、nd pairs shall be as specified in the table in clause 5 for contact numbers 3,4, 5 and 6. NOTE - Omission of contacts from positions 1, 2, 7 and 8 is to permit visual identificatiin of the 4-r&e cord. 3 ISO/IEC 8877:1992(E) NOTE - This portion of the plug illustrates a structure necessary for securi
4、ng the cordage and is not pertinent to proper mating with the jack Figure 1 - Plug - 8 pole Figure 2 - Jack - 8 pole 4 ISO/IEC 8877:1992(E) 9SZOlS9 A. 7 l19ZO) LL9 +$%+ ?O.O& m O& = (ZrLO) L9E m 5 ISO/IEC 8877:1992(E) Dimensions in millimetres (inches in parentheses) L-Plug contact I 1 The 24O min.
5、angle applies only to plugs with front plastic walls higher than 4.63 mm (0.190 in). 2 Jack contacts may be rectangular with a width of 0,50 10.019 5) max. and 0,36 (0.014) min. See note 2 0,5(0.0195) Figure 4 - Plug/jack contact specification 6 ISO/IEC 8877:1992(E) 4 (OEE0)8EE (lKO3998 I %16*99 1 I
6、 I I v- 1 _ i% .xe“J(OEZD) 98s z 7 ISO/IEC 8877:1992(E) Annex A (informative) Interface cabling arrangements! The interface cabling arrangements, implied by the requirements in CCITT Recommendation 1.430, section 4 are described in this annex. Figure A.1 illustrates the cabling arrangements, for the
7、 ISDN basic access interface, and shows the different parts of the physical interconnection: “connecting cords”, “extension cords” and “interface cables”. The same contact numbers assigned at the interface (point IA in CCITT Recommendation 1.430, figure Ul.430) of TEs for TRANSMIT and RECEIVE conduc
8、tor pairs are assigned at the interface (point IB in CCITT Recommendation 1.430, figure 2I.430) of NTs for RECEIVE and TRANSMIT . respectively, conductor pairs. This provides for a given conductor to be connected to the same contact in jacks at both ends of interface cables. However, it means that i
9、nterface cables are suitable for NT-to-TE and NT1 -to-NT2s interconnections only. For TE-to-TE interconnections, an adapter with a crossover to connect TRANSMIT to RECEIVE is required. Similar statements apply to contacts/conductors (pairs assigned to contact numbers l-2 and 7-8) used for optional p
10、ower transfer. As indicated in Recommendation 1.430, section 4, interface cables are terminated in the same type of connector part (jack) at both ends. This means that NTs or TEs may be connected at either end of point-to-point cables. Extension cords have a plug at one end and a jack at the other e
11、nd. They cannot be used to extend TE connecting cords in connections to Passive Bus wiring configurations because the bridging impedance of an extension cord (of even a short length) can adversely affect operation (including that of other TEs) in Passive Bus configurations. The length of the extensi
12、on cord(s) associated with a TE in point-to-point configurations is limited to 25 m. Connecting cords provide a plug for connection to an interface cable (or extension cord). The acceptable maximum length of such cords will generally be limited by the need for compliance with transmit and receive-ci
13、rcuit impedance requirements specified in CCITT Recommendation 1.430, section 8. While there is no restriction on the minimum length of such cords in a particular application , TEs are required to include a cord of at least 5 m in length . It is also significant that, in most ISDN applications, the
14、interface cable will be users premises wiring and the jack must be available in a form suitable for wall mounting. Available assemblies of the specified jack, which are intended for such mounting, may provide a housing for a suitable mounting of the transmit and receive pair terminating resistors. A
15、s specified in CCITT Recommendation 1.430, figure 2Il.430, the terminating resistors must be located, for point-to-point wiring configurations, in or at the jack and must be connected across contact pairs 4-5 and 3-6. For passive bus wiring configurations, the terminating resistors may be mounted in
16、 such jack assemblies located at the ends of the bus. It is equally important to recognize that the interface cable may be wired directly to NTs without the interface connector and with the interchange circuit terminating resistors provided internal to the equipment. This is possible where the cable
17、 is provided in association with or as part of the NT. In such applications, the only interface of significance (at which the requirements of CCITT Recommendation 1.430 apply) may be at the jack (point IA in CCITT Recommendation 1.430, figure Ul.430) for the connection of TEs . In addition, the comb
18、ination of the NT connecting cord and interface cabling may be of zero length. Another alternative NT connection arrangement uses a jack mounted on the NT equipment entity, which includes the terminating resistors. The jack may not conform to this International Standard, but where the jack does conform, the contact assignments shall be as specified. Where a cord, terminated at each end with a plug, is used to connect Interface cabling arrangements may be the subject of national regulations 8
