25 way male
25 way female
- 25 pin D-SUB male at the DTE (Computer)
- 25 pin D-SUB female at DCE (Modem)
- Direction is DTE (Computer) relative DCE (Modem)
- Do not connect SHIELD (pin 1) to GND (pin 7)
Pin | Name | Description | Direction |
1 | GND | Shield ground | --- |
2 | TXD | Transmit Data | --> |
3 | RXD | Receive Data | <-- |
4 | RTS | Request to send | --> |
5 | CTS | Clear to send | <-- |
6 | DSR | Data set ready | <-- |
7 | GND | System ground | --- |
8 | CD | Carrier detect | <-- |
9 | Reserved | ||
10 | Reserved | ||
11 | STF | Select transmit channel | --> |
12 | S.CD | Secondary carrier detect | <-- |
13 | S.CTS | Secondary clear to send | <-- |
14 | S.TXD | Secondary transmit data | --> |
15 | TCK | Transmission signal element timing | <-- |
16 | S.RXD | Secondary receive data | <-- |
17 | RCK | Receiver signal element timing | <-- |
18 | LL | Local loop control | --> |
19 | S.RTS | Secondary request to send | --> |
20 | DTR | Data terminal ready | --> |
21 | RL | Remote loop control | --> |
22 | RI | Ring indicator | <-- |
23 | DSR | Data signal rate selector | --> |
24 | XCK | Transmit signal element timing | --> |
25 | TI | Test indicator | <-- |
9 way male
9 way female
Pin | Name | Description | Direction |
1 | DCD | Data carrier detect | <-- |
2 | RXD | Receive data | <-- |
3 | TXD | Transmit data | --> |
4 | DTR | Data terminal ready | --> |
5 | GND | Signal ground | --- |
6 | DSR | Data set ready | <-- |
7 | RTS | Request to send | --> |
8 | CTS | Clear to send | <-- |
9 | RI | Ring indicator | <-- |
9 pin D-SUB female
9 pin D-SUB female
- DSR & CD are jumpered
Nullmodem cable (Female-Female)
Connector 1 | Pin | Connector 2 | Pin |
Receive data | 2 | Transmit data | 3 |
Transmit data | 3 | Receive data | 2 |
Data terminal ready | 4 | Data set ready + Carrier detect | 6+1 |
System ground | 5 | System ground | 5 |
Data set ready + Carrier detect | 6+1 | Data terminal ready | 4 |
Request to send | 7 | Clear to send | 8 |
Clear to send | 8 | Request to send | 7 |
9 pin D-SUB female
25 pin D-SUB female
Nullmodem cable (Female-Female)
Connector 1 (9w) | Pin | Connector 2 (25w) | Pin |
Receive data | 2 | Transmit data | 2 |
Transmit data | 3 | Receive data | 3 |
Data terminal ready | 4 | Data set ready + Carrier detect | 6 + 8 |
System ground | 5 | System ground | 7 |
Data set ready + Carrier detect | 6 + 1 | Data terminal ready | 20 |
Request to send | 7 | Clear to send | 5 |
Clear to send | 8 | Request to send | 4 |
25 pin D-SUB female
25 pin D-SUB female
Nullmodem cable (Female-Female)
Connector 1 | Pin | Connector 2 | Pin |
Receive data | 3 | Transmit data | 2 |
Transmit data | 2 | Receive data | 3 |
Data terminal ready | 20 | Data set ready + Carrier detect | 6+8 |
System ground | 7 | System ground | 7 |
Data set ready + Carrier detect | 6 + 8 | Data terminal ready | 20 |
Request to send | 4 | Clear to send | 5 |
Clear to send | 5 | Request to send | 4 |
9 pin D-SUB female
25 pin D-SUB male
Modem cable (Female-Male)
Description | Connector 1 (9w) | Connector 2 (25w) | Direction |
Transmit data | 3 | 2 | --> |
Receive data | 2 | 3 | <-- |
Request to send | 7 | 4 | --> |
Clear to send | 8 | 5 | <-- |
Data set ready | 6 | 6 | <-- |
System ground | 5 | 7 | --- |
Carrier detect | 1 | 8 | <-- |
Data terminal ready | 4 | 20 | --> |
Ring indicator | 9 | 22 | <-- |
Name | Name | Name | Name |
25 pin D-SUB female
25 pin D-SUB male
Modem cable (Female-Male)
Description | Connector 1 (Female) | Connector 2 (Male) | Direction |
Shield ground | 1 | 1 | --- |
Transmit data | 2 | 2 | --> |
Receive data | 3 | 3 | <-- |
Request to send | 4 | 4 | --> |
Clear to send | 5 | 5 | <-- |
Data set ready | 6 | 6 | <-- |
System ground | 7 | 7 | --- |
Carrier detect | 8 | 8 | <-- |
Data terminal ready | 20 | 20 | --> |
Ring indicator | 22 | 22 | <-- |
9 pin D-SUB Female
25 pin D-SUB Male
Two wire modem cable (Female-Male)
Description | Connector 1 (9w) | Connector 2 (25w) | Direction |
Shield ground | 1 | --- | |
Transmit data | 3 | 2 | --> |
Receive data | 2 | 3 | <-- |
System ground | 5 | 7 | --- |
Request to send + Clear to send | 7 - 8 | ||
Data set ready + Carrier detect + Data terminal ready | 6 - 1 - 4 | ||
Request to send + Clear to send | 4 - 5 | ||
Data set ready + Carrier detect + Data terminal ready | 6 - 8 - 20 |
25 pin D-SUB Female
25 pin D-SUB Male
Two wire modem cable (Female-Male)
Description | Connector 1 (Female) | Connector 2 (Male) | Direction |
Shield ground | 1 | 1 | --- |
Transmit data | 2 | 2 | --> |
Receive data | 3 | 3 | <-- |
System ground | 7 | 7 | --- |
Request to send + Clear to send | 4 - 5 | ||
Data set ready + Carrier detect + Data terminal ready | 6 - 8 - 20 | ||
Request to send + Clear to send | 4 - 5 | ||
Data set ready + Carrier detect + Data terminal ready | 6 - 8 - 20 |