RS-232, RS-422, RS-485
RS-232
Almost each PC with one serial interface (RS232C). This PC serial port interface is single ended (connects only two devices with each other), the data rate is less than 20 kbps. It's a voltage loop serial interface with full-duplex communication represented by voltage levels with respect to system ground. A common ground between the PC and the associated device is necessary.
| DB-9 Pin | Name | Dir | Description | 9 pin D-SUB male connector at the computer |
|---|---|---|---|---|
| 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 |
RS-422 (9 pin) connector pinout
| Pin | Signal | 9 pin D-SUB female connector |
|---|---|---|
| 1 | Tx- |  Pin out define by Manufacturers |
| 2 | Tx+ | |
| 3 | Rx+ | |
| 4 | Rx- |
RS-485 (9 pin) connector pinout
| Pin | Signal | 9 pin D-SUB female connector |
|---|---|---|
| 1 | Data- |  Pin out define by Manufacturers |
| 2 | Data+ |
