National Instruments NI 9225E User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9225E
3-Channel, 300 Vrms, 24-Bit, Simultaneous,
Channel-to-Channel Isolated Analog Input Module

NI 9225E Operating Instructions and Specifications 2 ni.com
This document describes how to use the National
Instruments 9225E and includes dimensions, terminal assignments,
and specifications for the NI 9225E. 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 9225E. The end-product supplier is responsible
for conformity to any and all compliance requirements.
Caution The NI 9225E must be installed inside a suitable
enclosure prior to use. Hazardous voltages may be present.

© National Instruments Corp. 3 NI 9225E Operating Instructions and Specifications
NI 9225E Dimensions
The following figure shows the dimensions of the NI 9225E.
Figure 1. NI 9225E Dimensions in Millimeters (Inches)
73.4 (2.89)
0.0 (0.00)
26.7 (1.05)
58.4 (2.30)
66.0 (2.60)
0.0 (0.00)

NI 9225E Operating Instructions and Specifications 4 ni.com
Connecting the NI 9225E
The NI 9225E has three 2-terminal detachable screw-terminal
connectors that provide connections for three simultaneously
sampled, isolated analog input channels.
Figure 2. NI 9225E Terminal Assignments
AI0+
AI0–
AI1+
AI1–
AI2+
AI2–
0
1
0
1
0
1

© National Instruments Corp. 5 NI 9225E Operating Instructions and Specifications
You can connect ground-referenced or floating signal sources to
the NI 9225E. 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 9225E, 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 9225E. Refer to the Specifications section for more
information about operating voltages and overvoltage protection.
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 9225E.
Refer to Figures 3 and 4 for illustrations of how to connect
grounded and floating signal sources to the NI 9225E.

NI 9225E Operating Instructions and Specifications 6 ni.com
Figure 3. Connecting a Grounded Signal Source to the NI 9225E
Figure 4. Connecting a Floating Signal Source to the NI 9225E
NI 9225E
Signal
Source
AI–
+
–
AI+
NI 9225E
Signal
Source
AI–
+
–
AI+

© National Instruments Corp. 7 NI 9225E Operating Instructions and Specifications
The NI 9225E 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 three channels simultaneously. Refer to
Figure 5 for an illustration of the circuitry for one channel of
the NI 9225E.
Figure 5. Input Circuitry for One Channel of the NI 9225E
NI 9225E
AI+
AI–
ADC
Amplifier
Overvoltage
Protection
Prefilter

NI 9225E Operating Instructions and Specifications 8 ni.com
Understanding NI 9225E Filtering
The NI 9225E 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 9225E 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 9225E 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 9225E.

© National Instruments Corp. 9 NI 9225E Operating Instructions and Specifications
Figure 6. Typical Passband Response of the NI 9225E
Frequency/Data Rate
0.50.4
0.025
0.000
–0.025
–0.050
0.30.20.10
Gain (dB)

NI 9225E Operating Instructions and Specifications 10 ni.com
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 9225E 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 9225E Data Rates
The frequency of a master timebase (fM) controls the data rate (fs)
of the NI 9225E. The NI 9225E 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 9225E with other
modules that use master timebases to control sampling, all of the

© National Instruments Corp. 11 NI 9225E Operating Instructions and Specifications
modules must share a single master timebase source. Refer to the
software help for information about configuring the master
timebase source for the NI 9225E. Visit ni.com/info and enter
cseriesdoc for information about C Series documentation.
The following equation provides the available data rates of the
NI 9225E:
fs=
where nis any integer from 1 to 31.
However, the data rate must remain within the appropriate data rate
range. Refer to the Specifications section for more information
about the data rate range. When using the internal master timebase
of 12.8 MHz, the result is data rates of 50 kS/s, 25 kS/s,
16.667 kS/s, and so on down to 1.613 kS/s, depending on the value
of n. When using an external timebase with a frequency other than
12.8 MHz, the NI 9225E has a different set of data rates.
Note The cRIO-9151 R Series Expansion chassis does
not support sharing timebases between modules.
fM256÷
n
---------------------

NI 9225E Operating Instructions and Specifications 12 ni.com
Sleep Mode
This module supports a low-power sleep mode. Support for sleep
mode at the system level depends on the chassis that the module is
plugged into. Refer to the chassis manual for information about
support for sleep mode. If the chassis supports sleep mode, refer to
the software help for information about enabling sleep mode. Visit
ni.com/info and enter cseriesdoc for information about
C Series documentation.
Typically, when a system is in sleep mode, you cannot
communicate with the modules. In sleep mode, the system
consumes minimal power and may dissipate less heat than it does
in normal mode. Refer to the Specifications section for more
information about power consumption and thermal dissipation.

© National Instruments Corp. 13 NI 9225E Operating Instructions and Specifications
Specifications
The following specifications are typical for the range –40 to 85 °C
unless otherwise noted. All voltages are relative to the AI– signal
on each channel unless otherwise noted.
Input Characteristics
Number of channels .......................... 3 analog input channels
ADC resolution................................. 24 bits
Type of ADC..................................... Delta-Sigma (with analog
prefiltering)
Sampling mode ................................. Simultaneous
Internal master timebase (fM)
Frequency ................................... 12.8 MHz
Accuracy..................................... ±100 ppm max
Data rate range (fs) using internal master timebase
Minimum.................................... 1.613 kS/s
Maximum ................................... 50 kS/s

NI 9225E Operating Instructions and Specifications 14 ni.com
Data rate range (fs) using external master timebase
Minimum.................................... 390.6 S/s
Maximum ................................... 51.2 kS/s
Data rates1(fs)................................... , n = 1, 2, ..., 31
Operating voltage ranges
Minimum.................................... 294 Vrms
Typical ........................................ 300 Vrms
Typical scaling coefficient ................ 50.66 μV/LSB
Overvoltage protection ..................... ±450 VDC
Input coupling................................... DC
Input impedance (AI+ to AI–) .......... 1 MΩ
1 The data rate must remain within the appropriate data rate range. Refer to the
Understanding NI 9225E Data Rates section for more information.
f
M256÷
n
---------------------

© National Instruments Corp. 15 NI 9225E Operating Instructions and Specifications
Accuracy
Input noise ........................................ 2 mVrms
Stability
Gain drift .................................... ±10 ppm/°C
Offset drift .................................. ±970 μV/°C
Post calibration gain match
(ch-to-ch, 20 kHz)............................. ±0.25 dB max
Measurement Conditions
Percent of
Reading
(Gain Error)
Percent of
Range*
(Offset Error)
Calibrated max (–40 to 70 °C) ±0.23% ±0.05%
Calibrated typ (25 °C, ±5 °C) ±0.05% ±0.008%
Calibrated max (25 °C, ±15 °C) ±0.084% ±0.016%
Uncalibrated max (– 40 to 70 °C) ±1.6% ±0.66%
Uncalibrated typ (25 °C, ±5 °C) ±0.4% ±0.09%
*Range equals 425 V.

NI 9225E Operating Instructions and Specifications 16 ni.com
Crosstalk (60 Hz).............................. –130 dB
Phase match
Ch-to-ch, max............................. 0.035°/kHz
Module-to-module, max............. 0.035°/kHz + 360° · fin/fM
Phase linearity (fs = 50 kS/s) ............. 0.22° max
Input delay ........................................ 38.4/fs+ 3 μs
Passband
Frequency ................................... 0.453 · fs
Flatness (fs = 50 kS/s) ................. ±100 mdB max
Stopband
Frequency ................................... 0.547 · fs
Rejection..................................... –100 dB
Alias-free bandwidth ........................ 0.453 · fs
–3 dB bandwidth (fs = 50 kS/s) ......... 24.56 kHz
CMRR (fin = 60 Hz).......................... –104 dB
SFDR (1 kHz, –60 dB) ..................... –128 dB

© National Instruments Corp. 17 NI 9225E Operating Instructions and Specifications
Total Harmonic Distortion (THD)
(1 kHz, –20 dB) ................................ –95 dB
MTBF ............................................... 301,606 hours at 25 °C;
Bellcore Issue 2, Method 1,
Case 3, Limited Part Stress
Method
Note Contact NI for Bellcore MTBF specifications
at other temperatures or for MIL-HDBK-217F
specifications.
Power Requirements
Power consumption from chassis
Active mode ............................... 495 mW max
Sleep mode ................................. 25 μW max
Thermal dissipation (at 70 °C)
Active mode ............................... 760 mW max
Sleep mode ................................. 265 mW max

NI 9225E Operating Instructions and Specifications 18 ni.com
Physical Characteristics
If you need to clean the module, wipe it with a dry towel.
Screw-terminal wiring ...................... 16 to 28 AWG copper
conductor wire with 7 mm
(0.28 in.) of insulation
stripped from the end
Torque for screw terminals ............... 0.22 to 0.25 N · m
(1.95to2.21lb·in.)
Ferrules ............................................. 0.25 mm2to 0.5 mm2
Weight............................................... 43 g (1.5 oz)
Safety
Maximum Voltage
Connect only voltages that are within the following limits.
AI+ to AI– ........................................ 300 Vrms max

© National Instruments Corp. 19 NI 9225E Operating Instructions and Specifications
Isolation Voltages
Channel-to-channel
Continuous ................................. 600 Vrms,
Measurement Category II,
(Basic insulation)
Withstand.................................... 2,300 Vrms, verified by a 5 s
dielectric withstand test
Channel-to-earth ground
Continuous ................................. 300 Vrms,
Measurement Category II,
(Double insulation)
Withstand.................................... 2,300 Vrms, verified by a 5 s
dielectric withstand test
Measurement Category II is for measurements performed on
circuits directly connected to the electrical distribution system.
This category refers to local-level electrical distribution, such as
that provided by a standard wall outlet, for example, 115 V for U.S.
or 230 V for Europe.
Caution Do not connect the NI 9225E to signals or use for
measurements within Measurement Categories III or IV.

NI 9225E Operating Instructions and Specifications 20 ni.com
Safety Standards
This product meets the requirements of the following standards of
safety for electrical equipment for measurement, control, and
laboratory use when installed in a suitable enclosure:
• IEC 61010-1, EN 61010-1
• UL 61010-1, CSA 61010-1
Note For UL and other safety certifications, refer to the
product label or the Online Product Certification section.
Online Product Certification
Refer to the product Declaration of Conformity (DoC) for
additional regulatory compliance information. To obtain product
certifications and the DoC for this product, visit ni.com/
certification, search by module number or product line, and
click the appropriate link in the Certification column.