Serial Port Interface F-1
This appendix provides information about the serial port interface for the Model XM128 ISDN
Digital Modem.
RS-232 Serial Interface
TableF-1 describes the RS-232 25-pin serial port interface for the Model XM128 modem.
Table F-1. Serial port int erface
Pin number ITU-TSS
signal name EIA
signal name Signal/pin description Signal direction
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. ?