Epson 4100 manual Appendix B Serial Interface, Serial Interface Basics

Appendix B—

Serial Interface

This appendix deals with RS-232-C (and RS-422-A) serial interface connectivity.

SERIAL INTERFACE BASICS

RS-232-C, commonly referred to as RS-232, is a serial interface communication standard developed by the Electronics Industries Association (EIA) which defines communication signals, pin assignments, and voltage levels.

The standard divides equipment into two categories:

•Data Terminal Equipment (DTE)

•Data Communication Equipment (DCE)

The two types of equipment are distinguished by their signals and pin assignments, as shown in the table on the following page:

•DTE devices transmit on Pin 2

•DCE devices transmit on Pin 3

Computers and serial printers are usually DTE devices. Modems and communication controllers are usually DCE devices.

The RS-232-C standard specifies more signals than are used, or needed, in most data communication applications. However, for reference, the table on the following page lists all communication signals, their