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CHAPTER 4: Option Selection
Figure 4-4. Headers E3 and E4, RS-485 Enable/Ground Selection.
4.4 Line Termination
Typically each end of the RS-422/485 bus must have line-terminating
resistors. A 100-ohm resistor is across each RS-422/485 input, and a 1K-ohm
pull-up/pull-down combination biases the receiver inputs. If more than two
RS-485 nodes are configured in a multidrop network, only the nodes at each
end of the bus should have the 100-ohm resistors installed.
A
B
C