Appendix F

Serial Port Interface

This appendix provides information about the serial port interface for the Model XM128 ISDN Digital Modem.

RS-232 Serial Interface

Table F-1 describes the RS-232 25-pin serial port interface for the Model XM128 modem.

Table F-1.

Serial port interface

 

 

 

 

 

 

 

Pin number

ITU-TSS

EIA

Signal/pin description

Signal direction

signal name

signal name

DTE -DCE

 

 

 

 

 

 

 

1

101

AA

Protective ground (GND).

¤

 

 

 

 

 

2

103

BA

Transmitted data (TXD).

?

 

 

 

 

 

3

104

BB

Received data (RXD).

 

 

 

 

 

4

105

CA

Request to send (RTS).

?

 

 

 

 

 

5

106

CB

Clear to send (CTS).

 

 

 

 

 

6

107

CC

Data set ready (DSR).

 

 

 

 

 

7

102

AB

Signal ground (GND).

¤

 

 

 

 

 

8

109

CF

Data carrier detected (DCD).

 

 

 

 

 

15

114

DB

Transmit clock signal (source: DCE).

 

 

 

 

 

17

115

DD

Synchronous receive clock.

 

 

 

 

 

18

141

 

Local analog loopback test.

?

 

 

 

 

 

20

108/2108/1

CD

Data terminal ready (DTR).

?

 

 

 

Connect DCE to line.

 

 

 

 

 

 

21

140

 

Remote digital loop test.

?

 

 

 

 

 

 

 

 

 

 

Serial Port Interface

 

 

F-1

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NETGEAR XM128 ISDN Appendix F Serial Port Interface, RS-232 Serial Interface, Table F-1 Serial port interface, Pin number