Table of Contents
RS232 vs RS485 vs RS422 :
| Sr No. | Parameter | RS -232 | RS – 422 | RS -485 |
| 1 | Wiring for communication | Single-ended | Differential | Differential |
| 2 | Signal type | Unbalanced | Balanced | Balanced |
| 3 | Output voltage | |||
| Logic 0 | + 5 to + 15 V w.r.t GND | + 2 to – 6 V on terminal A w.r.t B | + 2 to + 6 V on terminal A wr.t B | |
| Logic 1 | -5 to -15 v w.r.t GND | – 2 to – 6 V on terminal A w.r.t B | – 2 to – 6 V on terminal A wr.t B | |
| 4 | Data rate | 20 kbps (max) | 100 Mbps at 15 m 100 kpbs at 1200 m | 100 Mbps at 15 m 100 kpbs at 1200 m |
| 5 | Maximum cable length | 15 m | 1.2 km | 10 km |
| 6 | Maximum drivers | 1 | 1 | 32 |
| 7 | Maximum receivers | 1 | 7 | 32 |
| 8 | Source impedance | 300 Ω | 100 Ω | 100 Ω |
| 9 | Load impedance | 3 to 7 kΩ | 4 kΩ | |
| 10 | Direction | Uni-direction | Uni-direction | Bi-direction |
| 11 | Communication type | Full-duplex | Half-duplex – 2-wire full-duplex -4-wire | Half-duplex |
| 12 | Point-to-point/master-slave | Point-to-point | Master-slave | Master-slave |