Intelligent Technologies QCPort System Install Manual
November 2005
MN05001002E
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Page
16
Using Biasing Resistors
Depending on the type of QCPort system being implemented, biasing resistors may or
may not be required. For Figure 1 and Figure 2 under the “Interconnectivity Using
QCPort” section (One Device Using QCPort), a single biasing resistor is required when
the total length of the system is less than 3 feet [1 meter].
When connecting a Network Adapter to IO and motor controllers, as in Figure 3 Multiple
Devices Being Controlled And Monitored Remotely Using QCPort, biasing resistors are
required on the end furthest from the network Adapter. A biasing resistor is not required
on the one end that the Network Adapter is located since the Network Adapter has a
biasing resistor integral.
When a biasing resistor is required, use part # D77E-TERRJ or D77E-QPLR. These
biasing resistors connect between A and B and require 24V DC present on QCPort to be
functional. The D77E-QPLR has three connections to QCPort. They are through the RJ
connectors at the bottom, the Backplane connector on the back, and then through the
front connector at the A and B terminals. The D77E-TERRJ has only one way to connect
to QCPort, which is through the RJ connectors. There are two connectors that are in
parallel with each other so it is not important which way the biasing resistor is orientated.
Figure 10: QCPort Biasing Resistor Options
D77E-TERRJ
D77E-QPLR
P-
P+
A
B
P-
P+
-
+
-
+
-
+
Aux
Power
QCPort
Com
24V DC
