Adjustable Pull High/Low Resistors For The Rs-485 Port - Moxa Technologies NPort 5000 Series User Manual

B. Adjustable Pull High/low 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. Since there is no resistor value that works for every environment, DIP
switches or Jumpers are used to set the pull high/low resistor values for each RS-485 port.
ATTENTION
Do not use the 1 kΩ setting on NPorts when using the RS-232 interface. Doing so will degrade the RS-232
signals and shorten the maximum allowed communication distance.
NPort 5130/5150 Series (Jumpers)
To set a termination resistor to 150 kΩ, make sure that the two jumpers (JP3 and JP4) assigned to the
serial port are not shorted by jumper caps. This is the default setting.
To set a termination resistor to 1 kΩ, make sure that the two jumpers (JP3 and JP4) assigned to the
serial port are shorted by jumper caps.
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