Most Popular RS232 or Computer Serial Port Connectors
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 |
X.21 interface on a DB 15 connector
Fig. 2. X.12 DB15 connector
RJ-45 RS232 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
RJ45 RS232D connectors (same as telephone connectors)
| 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 | → | ← |
DB25 V.24 pinout and signals
Fig.4. RS232 V.24 connector
DB25 V.24 pinout and signals (ALT A connector)
Fig.5. RS232 V.24 (ALT A) connector
RS232 DB25 all pins (some applications require more pins)
Fig.6. RS232 DB25 connector
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