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RS-232 COM Port Pin Specifications C-2
RS-232 COM Port Pin Specifications
The asynchronous RS-232-D COM port on the 3C882 ISDN
modem, labeled RS-232, is a standard DB-25 female
connector. The 3C882 ISDN modem asynchronous port pin
assignments, shown in Table C-1, conform to standard
definitions for data communications equipment (DCE).
Table C-1 Pin Descriptions
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 (RI) From ISDN modem