3Com 56k User's Manual And Reference

Also see for U.S. Robotics 56K Voice: User guide Command reference User's guide and reference User guide User guide

3Com 56k User's Manual And Reference Manual pdf 77 page image

Technical Reference73The Serial InterfaceThe serial interface is a standard developed by the Electronic Industries Association (EIA). It defines thesignals and voltages used when data is exchanged between a computer and a modem or serial printer.The entire standard covers many more functions than are used in most data communications applications.Data is transmitted between the devices over a shielded serial cable with a 25-pin male (DB-25) connectorto the modem and a 25-pin, 9-pin, 8-pin, or custom-built connector to the computer.The use of a shielded cable when connecting a modem to a computer is recommended to ensure minimalinterference with radio and television.Pin assignments are factory-set in the U.S. Robotics modem to match the standard DB-25 assignments inthe following table. DB-9 connectors for IBM/AT-compatible computers should be wired at the computerend of the cable as shown in the DB-9 column.