3 – EIA-232 overview

Publisher Summary This chapter focuses on Electronic Industries Alliance (EIA)-232 standard and its characteristics. The EIA-232 interface standard was developed for the single purpose of interfacing data terminal equipment (DTE) and data circuit terminating equipment (DCE) employing serial binary data interchange. In particular, EIA-232 was developed for interfacing data terminals to modems. The EIA-232 standard consists of three major parts—namely, electrical signal characteristics, mechanical characteristics of the interface, and functional description of the interchange circuits. EIA-232 defines electrical signal characteristics such as the voltage levels and grounding characteristics of the interchange signals and associated circuitry for an unbalanced system. EIA-232 defines the mechanical characteristics of the interface between the DTE and the DCE. This dictates that the interface must consist of a plug and socket and that the socket should normally be on the DCE. EIA-232 defines the function of the data, timing and control signals used at the interface of the DTE and DCE. However, very few of the definitions are relevant to applications for data communications for instrumentation and control.