Fig.1 RS232/ V.24 DB9
| Pin | Name | Description |
|---|---|---|
| 1 | CD | Carrier Detect |
| 2 | RXD | Receive Data |
| 3 | TXD | Transmit Data |
| 4 | DTR | Data Terminal Ready |
| 5 | GND | System Ground |
| 6 | DSR | Data Set Ready |
| 7 | RTS | Request to Send |
| 8 | CTS | Clear to Send |
| 9 | RI | Ring Indicator |
Fig. 2. X.12 DB15 connector
EIA-561 defined RS232 on RJ 45 (modular) connector. It can be used only for non-synchronous applications because it does not have synchronous clocking signals. Note: The RI pin (#1) sometimes can be used as DSR.
Fig.3. RJ-45 RS232 connector
| Pin No. | Signal Description | Abbr. | DTE | DCE |
|---|---|---|---|---|
| 1 | DCE Ready, Ring Indicator | DSR/RI | ← | → |
| 2 | Received Line Signal Detector | DCD | ← | → |
| 3 | DTE Ready | DTR | → | ← |
| 4 | Signal Ground | SG | ||
| 5 | Received Data | RxD | ← | → |
| 6 | Transmitted Data | TxD | → | ← |
| 7 | Clear To Send | CTS | ← | → |
| 8 | Request To Send | RTS | → | ← |
Fig.4. RS232 V.24 connector
Fig.5. RS232 V.24 (ALT A) connector
Fig.6. RS232 DB25 connector