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UPort 1100 Series User’s Manual Introduction
1-5
TR
150 KX
1K
21
ON DIP
3
Adjustable Pull High/low, Terminator Resistors for the RS-485 Port
In some critical environments, you may need to add termination resistors to prevent the reflection
of serial signals. When using termination resistors, it is important to set the pull high/low resistors
correctly so that the electrical signal is not corrupted. The UPort uses DIP switches to set the pull
high/low resistor values for each serial port.
To set the pull high/low resistors to 150 KΩ, make sure both of the assigned DIP switches are in
the OFF position. This is the default setting.
To set the pull high/low resistors to 1 KΩ, make sure both of the assigned DIP switches are in
the ON position.
1 2 3
SW
Pull High Pull Low Terminator
ON
1KΩ 1KΩ 120 Ω
OFF
150 KΩ 150 KΩ Disable