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Chapter 2
Using the Module
Figure 2-6 shows the PXIe-4480/4481 voltage input connection with the terminals in
pseudodifferential configuration.
Figure 2-6.
PXIe-4480/4481 Voltage Input Connection in Pseudodifferential Configuration
Figure 2-7 shows the PXIe-4480 input connection for the charge mode channel type.
Figure 2-7.
PXIe-4480 Charge Input Connection
Refer to the
Measurement System Types and Signal Sources
topic in the
NI-DAQmx Help
for
more information about terminal configurations.
Input Coupling
You can configure the PXIe-4480/4481 modules for either AC or DC coupling. If you select
DC coupling, any DC offset present in the source signal is passed to the ADC. The DC-coupled
configuration is usually best if the signal source has only small amounts of offset voltage or if
the DC content of the acquired signal is important. If the source has a significant amount of
unwanted offset, select AC coupling to take full advantage of the input dynamic range.
Selecting AC coupling enables a highpass RC filter into the signal conditioning path. Using
AC coupling results in an attenuation of the low-frequency response of the AI circuitry. Refer to
the
PXIe-4480/4481 Specifications
for information about the cut-off frequency for the device.
For maximum flexibility, the module’s input coupling is programmable on a per-channel basis.
+
–
1.62 M
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50
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Volt
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S
o
u
rce
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–
PXIe-44
8
0/44
8
1
AI–
AI+
–
+
Ch
a
rge
S
en
s
or
PXIe-44
8
0
AI–
AI+