Reference Guide for the Model XM128 ISDN Digital Modem

F-2 Serial Port Interface

Asynchronous Cable Connections

TableF-2 provides information about the asynchronous flow control cable connection.

22 125 CE Ring indicator (RI).
24 113 DA Transmit clock signal (source: DTE). ?
25 142 Test indicator.

TableF-2. Asynchronous flow control cable connection

Modem
(DCE) DB25 Signal To PC
(DTE) DB 9 To DCE
(Null) DB25 To
MAC Mini 8 To N eXT
68,040 Mini 8
2TXD3333
3RXD2255
4RTS7516
5CTS8428
6DSR620
7 Ground 5 7 4,8 4
8 CD (DCD) 1 20 2
20 DTR 4 6,8 1 1
22 RI 9

TableF-1. Serial port interface (continued)

Pin number ITU-TSS
signal name EIA
signal name Signal/pin description Signal direction
DTE -DCE