Inside RS-232
Table 4-4: In addition to RS-232, there are several other EIA/TIA interfaces for
unbalanced lines.
+"')/)'1 +"2"'-)/' +"'*3) +"'*/4'
Cable length, max
(ft), unshielded
cable, 20pF/ft,
100kbps
50 50 15 ft @ 64kbps 4000
Data rate, max
(bps)
20k 100k 64k 2.1M
Driver output
(minimum, V)
± 5 ± 3.6 ±3.3 ± 3.3, ±2*
Driver output
(maximum, V)
± 15 ± 6 ±13.2 ±6, ±10*
Receiver
sensitivity (V)
± 3 ± 0.2 ± 3 ±0.2
Maximum
number of drivers
1111
Maximum
number receivers
110110
Receiver input
resistance (Ω)
3k-7k 450 (minimum) 3k-7k 450, 4k*
*Data and some control lines use a balanced interface. Other signals use an unbalanced interface.
Figure 4-6: An RS-423 interface can have just one transmitter but can have up to ten
receivers.