© National Instruments Corp. 9 NI 9478 Operating Instructions and Specifications
Protecting the Module from Flyback Voltages
If the module is switching an inductive or energy-storing device
such as a solenoid, motor, or relay, and the device does not have
flyback protection, install an external flyback diode as shown in
Figure3. Refer to the Using Long Cables section for more
information about protection from cable inductance flyback.
Figure 3. Connecting a Flyback Diode to the NI 9478
+
–
NI 9478
COM
DO External
Power
Supply
Vsup
Cable
Clamp Device