©
National Instruments Corp.
9
NI 9233 Operating Instructions and Specifications
The NI 9233 analog inp
u
t channels are referenced to the chassis
gro
u
nd thro
u
gh a 50
Ω
resistor. To minimize gro
u
nd noise, make
s
u
re that the chassis gro
u
nd is connected to the earth gro
u
nd. Each
channel is protected from overvoltages. The NI 9233 provides
an IEPE excitation c
u
rrent for each inp
u
t signal. The signal is
AC-co
u
pled, b
u
ffered, and conditioned. The signal is then sampled
by a 24-bit Delta-Sigma ADC. The NI 9233 IEPE excitation
c
u
rrent and AC co
u
pling are always enabled. Refer to Fig
u
an ill
u
stration of the inp
u
t circ
u
itry for one channel of the NI 9233.
Figure 4.
Input Circuitry for One Channel of the NI 9233
NI 9233
AI+
AI–
50
Ω
ADC
Amplifier
and
Prefilter
Excitation
Current
AC
Coupling
+
