National Instruments NI 9478 - Manual (Page 8)

NI 9478 Operating Instructions and Specifications 8 ni.com
Connect the device to DO and the positive lead of the power
supply. Refer to Figure 2 for an illustration of how to connect
a device to the NI 9478.
Figure 2. Connecting a Device to the NI 9478
You must connect the V
sup
pin to the power supply to enable a
weak cable clamping diode that protects the module from cable
inductance flyback. This flyback voltage results from small
amounts of energy stored in the inductance of the cabling. Refer
to the
Using Long Cables section for more information about
protection from cable inductance flyback. You still must install an
external flyback diode when switching inductive loads. Refer to the
Protecting the Module from Flyback Voltages section for more
information about installing a flyback diode.
Device
+
–
NI 9478
COM
V
sup
DO
External
Power
Supply
Cable
Clamp