PIN ASSIGNMENTS
DB-9 Port Pin Assignments
EIA | CCITT | Description | Switch’s | PC DB9 | Modem | Signal |
Circuit | Signal |
| DB9 DTE | DTE | DB25 | Direction |
|
|
| Pin # | Pin # | DCE Pin # | |
CF | 109 | DCD (Data Carrier Detected) | 1 | 1 | 8 | |
BB | 104 | RxD (Received Data) | 2 | 2 | 3 | |
BA | 103 | TxD (Transmitted Data) | 3 | 3 | 2 | |
CD | 108.2 | DTR (Data Terminal Ready) | 4 | 4 | 20 | |
AB | 102 | SG (Signal Ground) | 5 | 5 | 7 | |
CC | 107 | DSR (Data Set Ready) | 6 | 6 | 6 | |
CA | 105 | RTS | 7 | 7 | 4 | |
CB | 106 | CTS | 8 | 8 | 5 | |
CE | 125 | RI (Ring Indicator) | 9 | 9 | 22 |
Console Port to 9-Pin COM Port on PC
Switch’s |
| CCITT Signal |
| PC’s | |
| Serial Port |
|
|
| COM Port |
|
|
|
|
|
|
1 | DCD | DCD | 1 | ||
2 | RXD | TXD | 3 | ||
3 | TXD | RXD | > | 2 | |
4 | DTR | DSR | > | 6 | |
5 | SGND | SGND | 5 | ||
6 | DSR | DTR | 4 | ||
7 | RTS | CTS | > | 8 | |
8 | CTS | RTS | 7 | ||
9 | RI | RI | 9 |
Console Port to 25-Pin DCE Port on Modem
Switch’s |
| CCITT Signal |
| Modem’s |
Serial Port |
|
|
| DCE Port |
|
|
|
|
|
1 | < | 8 | ||
2 | < | 3 | ||
3 | TXD | > | 2 | |
4 | DTR | > | 20 | |
5 | SGND | 7 | ||
6 | < | 6 | ||
7 | RTS | > | 4 | |
8 | < | 5 | ||
9 | < | 22 |