Technical Specifications C-3
RS-232-D pin assignments
The asynchronous RS-232-D port on the ISDN modem, labeled
RS232, is a standard DB-25 female connector. The ISDN modem
asynchronous port pin assignments, shown in the following table,
conform to standard definitions for data communications equipment
(DCE).
Pin # Pin Name Signal Direction
1 Shield Ground (GND) —
2 Send Data (SD) To ISDN modem
3 Receive Data (RD) From ISDN modem
4 Request to Send (RTS) To ISDN modem
5 Clear to Send (CTS) From ISDN modem
6 Data Set Ready (DSR) From ISDN modem
7 Signal Ground (GND) —
8 Carrier Detect (DCD) From ISDN modem
18 Local Loopback From ISDN modem
20 Data Terminal Ready (DTR) To ISDN modem
21 Remote Loopback To ISDN modem
22 Ring Indicator (R) From ISDN modem