National Instruments NI 9229E User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9229E/9239E
4-Channel, ±60/±10 V, 24-Bit Simultaneous,
Channel-to-Channel Isolated Analog Input Modules

NI 9229E/9239E 2 ni.com
This document describes how to use the National
Instruments 9229E and National Instruments 9239E and includes
dimensions, terminal assignments, and specifications. In this
document, the NI 9229E and NI 9239E are referred to inclusively
as the NI 9229E/9239E. Visit ni.com/info and enter
rdsoftwareversion to determine which software you need for
the modules you are using. For information about installing,
configuring, and programming the system, refer to the system
documentation. Visit ni.com/info and enter cseriesdoc for
information about C Series documentation.
Caution National Instruments makes no electromagnetic
compatibility (EMC) or CE marking compliance claims
for the NI 9229E/9239E. The end-product supplier is
responsible for conformity to any and all compliance
requirements.
Caution The NI 9229E/9239E must be installed inside a
suitable enclosure prior to use. Hazardous voltages may be
present.

© National Instruments Corp. 3 NI 9229E/9239E
NI 9229E/9239E Dimensions
The following figure shows the dimensions of the NI 9229E/9239E.
Figure 1. NI 9229E/9239E Dimensions in Millimeters (Inches)
0.0 (0.00)
26.7 (1.05) 58.4 (2.30) 66.0 (2.60)
73.4 (2.89)
0.0 (0.00)

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Connecting the NI 9229E/9239E
The NI 9229E/9239E provides connections for four
simultaneously sampled, isolated analog input channels.
Figure 2. NI 9229E/9239E Terminal Assignments
AI0+
AI0–
AI1+
AI1–
AI2+
AI2–
AI3+
AI3–
0
1
0
1
0
1
0
1

© National Instruments Corp. 5 NI 9229E/9239E
The NI 9229E/9239E has four 2-terminal detachable
screw-terminal connectors.
Note You must use 2-wire ferrules to create a secure
connection when connecting more than one wire to a
single terminal on the NI 9229E /9239E.
You can connect ground-referenced or floating signal sources to
the NI 9229E/9239E. Connect the positive signal of the signal
source to the AI+ terminal, and connect the negative signal of the
signal source to the AI– terminal. If you make a ground-referenced
connection between the signal source and the NI 9229E/9239E,
make sure the voltage on the AI+ and AI– connections are in the
channel-to-earth safety voltage range to ensure proper operation of
the NI 9229E/9239E. Refer to the Specifications section for more
information about operating voltages and overvoltage protection.
Refer to Figures 3 and 4 for illustrations of how to connect
grounded and floating signal sources to the NI 9229E/9239E.

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Figure 3. Connecting a Grounded Signal Source to the NI 9229E/9239E
Figure 4. Connecting a Floating Signal Source to the NI 9229E/9239E
NI 9229E/9239E
Signal
Source
AI–
+
–
AI+
NI 9229E/9239E
Signal
Source
AI–
+
–
AI+

© National Instruments Corp. 7 NI 9229E/9239E
The NI 9229E/9239E analog input channels are floating with
respect to earth ground and each other. The incoming analog signal
on each channel is conditioned, buffered, and then sampled by a
24-bit Delta-Sigma ADC.
Each channel provides an independent signal path and ADC,
enabling you to sample all four channels simultaneously. Refer
to Figure 5 for an illustration of the circuitry for one channel.
Figure 5. Input Circuitry for One Channel of the NI 9229E/9239E
NI 9229E/9239E
AI+
AI–
ADC
Amplifier
Overvoltage
Protection
Prefilter

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Understanding NI 9229E/9239E Filtering
The NI 9229E/9239E uses a combination of analog and digital
filtering to provide an accurate representation of in-band signals
while rejecting out-of-band signals. The filters discriminate
between signals based on the frequency range, or bandwidth, of
the signal. The three important bandwidths to consider are the
passband, the stopband, and the alias-free bandwidth.
The NI 9229E/9239E represents signals within the passband, as
quantified primarily by passband flatness and phase nonlinearity.
All signals that appear in the alias-free bandwidth are either
unaliased signals or signals that have been filtered by at least
the amount of the stopband rejection.
Passband
The signals within the passband have frequency-dependent gain or
attenuation. The small amount of variation in gain with respect to
frequency is called the passband flatness. The digital filters of the
NI 9229E/9239E adjust the frequency range of the passband to
match the data rate. Therefore, the amount of gain or attenuation at
a given frequency depends on the data rate. Figure 6 shows typical
passband flatness for the NI 9229E/9239E.

© National Instruments Corp. 9 NI 9229E/9239E
Figure 6. Typical Passband Flatness for the NI 9229E/9239E
Frequency/Data Rate
0.50.4
0.025
0.000
–0.025
–0.050
0.30.20.10
Gain (dB)

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Stopband
The filter significantly attenuates all signals above the stopband
frequency. The primary goal of the filter is to prevent aliasing.
Therefore, the stopband frequency scales precisely with the data
rate. The stopband rejection is the minimum amount of attenuation
applied by the filter to all signals with frequencies within the
stopband.
Alias-Free Bandwidth
Any signal that appears in the alias-free bandwidth of the
NI 9229E/9239E is not an aliased artifact of signals at a higher
frequency. The alias-free bandwidth is defined by the ability of the
filter to reject frequencies above the stopband frequency and equals
the data rate minus the stopband frequency.
Understanding NI 9229E/9239E Data Rates
The frequency of a master timebase ( fM) controls the data rate ( fs)
of the NI 9229E/9239E. The NI 9229E/9239E includes an internal
master timebase with a frequency of 12.8 MHz, but the module
also can accept an external master timebase or export its
own master timebase. To synchronize the data rate of an
NI 9229E/9239E with other modules that use master timebases