8
FP-1000/1001 Quick Start Guide
ni.com
Connecting the FP-1001 to a Computer’s RS-485 Serial Port
You may connect up to 25 FP-1001 network modules to a single RS-485 port of a host
computer. Use the connection shown in this figure.
A. Connect the FP-1001 to a host
computer using the 5-position
Combicon screw terminal adapter
of the RS-485 connector on the
FP-1001.
B. Install the 120
Ω
termination
resistors included with the
FP-1001. Install them between the
RX and TX pair of the host
computer RS-485 port, and
between the RX and TX pair on the
RS-485 port of the last FP-1001 in
the system, as shown. Twist the
resistor leads with the RS-485
signal wires and insert them into
the RS-485 port terminals.
C. Check the biasing feature. The
host computer RS-485 interface
usually provides for biasing
resistors, which are required on
an RS-485 network. You should use
this biasing feature for better
reliability and noise immunity.
FP-1001
TX+
TX-
GND
RX+ RX-
FP-1001
TX+
TX-
GND
RX+ RX-
RX
RX
RX
TX
TX
TX
FP-1001
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