3Com 005699-00 Manual

Also see for 005699-00 -: Installation guide

TECHNICAL R EFERENCE8-37The Serial InterfaceThe serial interface is a standard developed by the Electronic IndustriesAssociation (EIA). It defines the signals and voltages used when data isexchanged between a computer and a modem or serial printer.The entire standard covers many more functions than are used in most datacommunications applications. Data is transmitted between the devices over ashielded serial cable with a 25-pin male (DB-25) connector to the modem and a25-pin, 9-pin, 8-pin, or custom-built connector to the computer.FCC regulations require the use of a shielded cable when connecting a modem toa computer to ensure minimal interference with radio and television.Pin assignments are factory-set in the U.S. Robotics modem to match thestandard DB-25 assignments in the following table. DB-9 connectors forIBM/AT-compatible computers should be wired at the computer end of the cableas shown in the DB-9 column.