3 - Serial communication standards

Abstract

This chapter discusses the main physical interface standards associated with data communications for instrumentation and control systems. An interface standard defines the electrical and mechanical details that allow equipment from different manufacturers to be connected and be able to communicate. The RS have produced several well-known data interface standards, including RS-232 and revisions, RS-449, RS-423, RS-422, RS-485, RS/TIA-530A, and RS/TIA-562. The RS-232 interface standard was developed for the single purpose of providing an interface between data terminal equipment (DTE) and data circuit terminating equipment (DCE) employing serial binary data interchange. In particular, RS-232 was developed for interfacing data terminals to modems. This chapter includes information on balanced and unbalanced transmission lines, current loops, and serial interface converters. It also explains the functions of the important standards organizations, and compares the serial data communications interface standards, including RS-232, RS-449, RS-423, RS-422, RS-485, RS/TIA-530A, and RS/TIA-562. The chapter explains troubleshooting in serial data communication circuits, and describes commonly used serial interface techniques, such as 20 mA current loop, serial interface converters, and interface to serial printers. The chapter also describes the most important parallel data communication interface standards, including general purpose interface bus and centronics.