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PCI 1 Port RS422/485
ADDITIONAL RS422/485
The RS422 Standard.
The RS422 standard defines a serial communications
standard. RS422 is a high speed and/or long distance data
transmission. Each signal is carried by a pair of wires and is thus a
differential data transmission system. Over distances up to 40 feet
the maximum data rate is 10 Megabits per second, and for
distances up to 4000 feet the maximum data rate is 100 Kilobytes
per second. A 120-Ohm resistor should be used to terminate the
receiving end of the line. It is generally used between one
transmitter receiver pair to ONLY one other transmitter receiver
pair, but each output can drive up to 10 receivers.
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The RS485 Standard.
The RS485 standard is similar to the RS422 standard upon
which it is based. The main difference is that up to 32 transmitter
receiver pairs may be present on the line at one time. A 120-Ohm
resistor should be used to terminate either end of the main line. If
Chapter 4
OPERATION
RS422 Standard
1 Driver up to 10 Receivers
Line Length
40 Feet =
400 Feet = 122m
4000 Feet = 1219m
'
Chapter 3 Page 53
Max Data Rate
12m
10 Mbits/sec
100 Kbits/sec
Software Setup
1 Mbits/sec
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