Pinout RS-232
A Data Communications Equipment (DCE) can be interfaced to a Data Terminal Equipment (DTE) using a straight through serial cable. Typically, PC’s are defined as a DTE and peripherals are defined as DCE. To interface a DCE with another DCE, or a DTE with another DTE, a null modem (or a Crossover) cable is required. The null modem simply swaps pins to convert a DCE to a DTE and vice-versa.
| 9 pin | 25 pin | DTE | DTE Signal Name | DTE Direction | DCE | DCE Signal Name | DCE Direction | Description |
|---|---|---|---|---|---|---|---|---|
| 1 | 8> | DCD | Data Carrier Detect | IN | DCD | Data Carrier Detect | OUT | Modem connected to another |
| 2 | 3 | RxD | Receive Data | IN | TxD | Transmit Data | OUT | Receives bytes into the PC |
| 3 | 2 | TxD | Transmit Data | OUT | RxD | Receive Data | IN | Transmits bytes out of the PC |
| 4 | 20 | DTR | Data Terminal Ready | OUT | DTR | Data Terminal Ready | IN | I’m ready to communicate |
| 5 | 7 | SG | Signal Ground | SG | Signal Ground | |||
| 6 | 6 | DSR | Data Set Ready | IN | DSR | Data Set Ready | OUT | I’m ready to communicate |
| 7 | 4 | RTS | Request To Send | OUT | RTS | Request To Send | IN | RTS/CTS flow control |
| 8 | 5 | CTS | Clear To Send | IN | CTS | Clear To Send | OUT | RTS/CTS flow control |
| 9 | 22 | RI | Ring Indicator | IN | RI | Ring Indicator | OUT | Telephone line ringing |