TIA RS-423-A PDF

This Standard specifies the electrical characteristics of the unbalanced voltage digital interface circuit, normally implemented in integrated circuit technology, that may be employed when specified for the interchange of serial binary signals between Data Terminal Equipment (DTE) and Da'bl CircuitTerminating Equipment (DCE) or in any point-to-point interconnection of serial binary signals between digital equipment.

This Standard was developed in liaison with the International Organization for Standardization (ISO) and the International Telegraph and Telephone Consultative Committee (CCITT). It is compatible with CCITT Recommendations V.lO and X.26.

The interface circuit includes a generator connected by an interconnecting cable to a load consisting of a receiver or receivers. The electrical characteristics of the circuit are specified in terms of required voltage, current and resistance values obtained from direct measurement of the geneNtor and receiver components. The requirements for signal wave shaping, generally necessary to reduce unbalanced circuit near-end crosstalk to adjacent circuits, are also described. The receiver specification for the unbalanced interface is electrically identical to that specified for the balanced interface circuit in RS-422·A. Minimum performance requirements for the interconnecting cable are furnished. Guidance is given in Appendix A.l with respect to limitations on data signalling rate imposed by the parameters of cable length and generation of near-end crosstalk.

The parameter values specified for the unbalanced generator and load components of the interface are designed such that unbalanced interface circuits may be used within the same interconnection as balanced interface circuits specified by RS-422-A. For example, the balanced circuits may be used for data and timing while the unbalanced circuits may be used for low speed control functions. In addition, interoperation may be possible under certain conditions with generators and receivers of other digital interface standards such as EIA Standard RS-232-C.

It is intended that this Standard will be referenced by other standards that specify the complete DTE/DCE interface (i.e., protocol, timing, pin assignments, etc.) for applications where the electrical characteristics of an unbalanced voltage digital interface circuit are required. Applications are also foreseen in other areas using binary signal interchange. This Standard does n(\t specify other characteristics of the DTE/ DCE interface (such as signal quality and timing, etc.) et~sential for the interconnected equipment operation. When this Standard is referenced by other standards or specifications, it should be noted that certain options are available. The preparer of those referencing standards and specifications must determine and specify those optional features which are required for that application.