RS 232 / RS485 / RS422 – forskel?

 

RS232 RS422 RS485
Cabling single ended single ended
multi-drop
multi-drop
Number of Devices 1 transmit
1 receive
5 transmitters
10 receivers
32 transmitters
32 receivers
Communication Mode full duplex full duplex
half duplex
half duplex
Max. Distance 50 feet at 19.2 Kbps 4000 feet at 100 Kbps 4000 feet at 100 Kbps
Max. Data Rate 19.2 Kbps for 50 feet 10 Mpbs for 50 feet 10 Mpbs for 50 feet
Signaling unbalanced balanced balanced
Mark (data 1) -5 V min.
-15 V max.
2 V min. (B>A)
6 V max. (B>A)
1.5 V min. (B>A)
5 V max. (B>A)
Space (data 0) 5 V min.
15 V max.
2 V min. (A>B)
6 V max. (A>B)
1.5 V min. (A>B)
5 V max. (A>B)
Input Level Min. +/- 3 V 0.2 V difference 0.2 V difference
Output Current 500 mA 150 mA 250 mA