National Instruments NI 9478, Руководство по эксплуатации

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NI 9478 Operating Instructions and Specifications 10 ni.com
Using Long Cables
The ind u ctance of the cabling that connects the NI 9478, the loads,
and the external s u pply stores u p energy when a channel is on and
passing c u rrent thro u gh the cables. Each time a channel is t u rned
off, the energy stored in the cables is released as flyback voltage
and dissipates as heat in the NI 9478. The total power dissipated in
the mod
u le increases with higher switching freq u encies, higher
c u rrents, and longer cable lengths. The cable length is the total
distance from the digital o u tp u t pin of the NI 9478 channel,
thro u gh the load, thro u gh the external power s u pply, and back
to the COM pin, as shown in Fig u re 4.
Figure 4. Cable Length of the NI 9478
NI 947 8
COM
V
su p
DO
+
–
External
Power
S
u pply
Cable
Length
Load
Cable
Clamp