cabling is released as flyback voltage, which dissipates as heat in
the NI 9478. The heat dissipated increases with higher switching
frequencies, higher currents, and longer cables.
Reducing Cable Length
The effective cable length is the total distance from DO to COM.
Figure 3.
Cable Length of the NI 9478
NI 9478
COM
Vsup
DO
+
–
External
Power
Supply
Cable
Length
Load
Cable
Clamp
NI recommends adding a capacitor across the power supply leads
and a diode from the DO lead to the Vsup lead. Connecting a
capacitor and a diode reduces the effective cable length and
dissipated heat.
14
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NI 9478 Getting Started Guide
