This document describes how to use the National Instruments 9225
and includes specifications and pin assignments for the NI 9225.
NoteThe safety guidelines and specifications in this
document are specific to the NI 9225. The other
components in the system might not meet the same safety
ratings and specifications. Refer to the documentation for
each component in the system to determine the safety
ratings and specifications for the entire system.
Related Information
NI CompactDAQ &
NI CompactRIO Documentation
ni.com/info cseriesdoc
Software Support
ni.com/info softwareversion
2|ni.com|NI 9225 Operating Instructions and Specifications
Chassis Compatibility
ni.com/info compatibility
Services
ni.com/services
Page 3
Safety Guidelines
Operate the NI 9225 only as described in these operating
instructions.
Hot SurfaceThis icon denotes that the component may
be hot. Touching this component may result in bodily
injury.
Hazardous Voltage This icon denotes a warning
advising you to take precautions to avoid electrical
shock.
CautionDo not operate the NI 9242 in a manner not
specified in this manual. Product misuse can result in a
hazard. You can compromise the safety protection built
into the product if the product is damaged in any way. If
the product is damaged, return it to National Instruments
for repair.
Safety Guidelines for Hazardous Voltages
If hazardous voltages are connected to the module, take the
following precautions. A hazardous voltage is a voltage greater
than 42.4 V
performed only by qualified personnel adhering to local
electrical standards.
CautionDo not mix hazardous voltage circuits and
human-accessible circuits on the same module.
CautionMake sure that devices and circuits connected
to the module are properly insulated from human contact.
CautionWhen module terminals are hazardous voltage
LIVE (>42.4 V
/60 VDC), you must ensure that devices
pk
and circuits connected to the module are properly
insulated from human contact. You must use the NI 9971
connector backshell kit to ensure that the terminals are
not accessible.
4|ni.com|NI 9225 Operating Instructions and Specifications
The NI 9225 is suitable for use in Class I, Division 2, Groups A, B,
C, D, T4 hazardous locations; Class I, Zone 2, AEx nA IIC T4, and
Ex nA IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if you are installing the NI 9225 in a
potentially explosive environment. Not following these guidelines
may result in serious injury or death.
CautionDo not disconnect I/O-side wires or connectors
unless power has been switched off or the area is known
to be nonhazardous.
CautionDo not remove modules unless power has been
switched off or the area is known to be nonhazardous.
CautionSubstitution of components may impair
suitability for Class I, Division 2.
CautionFor Zone 2 applications, install the system
in an enclosure rated to at least IP 54 as defined by
IEC 60529 and EN 60529.
6|ni.com|NI 9225 Operating Instructions and Specifications
Page 7
Special Conditions for Marine Applications
Some modules are Lloyd’s Register (LR) Type Approved for
marine applications. To verify Lloyd’s Register certification, visit
ni.com/certification and search for the LR certificate, or
look for the Lloyd’s Register mark on the module.
CautionTo meet radio frequency emission
requirements for marine applications, use shielded cables
and install the system in a metal enclosure. Suppression
ferrites must be installed on power supply inputs near
power entries to modules and controllers. Power supply
and module cables must be separated on opposite sides of
the enclosure and must enter and exit through opposing
enclosure walls.
The NI 9225 has three 2-terminal detachable screw-terminal
connectors that provide connections for three simultaneously
sampled, isolated analog input channels.
Figure 2. NI 9225 Terminal Assignments
AI0+
AI0–
AI1+
AI1–
AI2+
AI2–
0
1
0
1
0
1
8|ni.com|NI 9225 Operating Instructions and Specifications
Page 9
You can connect ground-referenced or floating signal sources to
the NI 9225. 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 9225, 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 9225. Refer to
the Specifications section for more information about operating
voltages and overvoltage protection.
NoteYou must use 2-wire ferrules to create a secure
connection when connecting more than one wire to a
single terminal on the NI 9225.
Refer to Figures 3 and 4 for illustrations of how to connect
NI 9225
Signal
Source
AI–
+
–
AI+
NI 9225
Signal
Source
AI–
+
–
AI+
grounded and floating signal sources to the NI 9225.
Figure 3. Connecting a Grounded Signal Source to the NI 9225
Figure 4. Connecting a Floating Signal Source to the NI 9225
10|ni.com|NI 9225 Operating Instructions and Specifications
Page 11
The NI 9225 analog input channels are floating with respect to
NI 9225
AI+
AI–
ADC
Amplifier
Overvoltage
Protection
Prefilter
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 9225.
Figure 5. Input Circuitry for One Channel of the NI 9225
If an application is subject to high vibration, National Instruments
recommends that you either use ferrules to terminate wires to the
detachable screw-terminal connector or use the NI 9971 backshell
kit to protect the connections. Refer to Figure 6 for an illustration
of using ferrules. Refer to Figure 1 for an illustration of the
NI 9971 connector backshell.
Figure 6. 2-Terminal Detachable Screw-Terminal Connector with Ferrule
12|ni.com|NI 9225 Operating Instructions and Specifications
Page 13
Understanding NI 9225 Filtering
The NI 9225 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 9225 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 9225 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 7 shows typical
passband flatness for the NI 9225.
Figure 7. Typical Passband Response of the NI 9225
0.025
0.000
Gain (dB)
–0.025
–0.050
0.30.20.10
Frequency/Data Rate (Hz)
14|ni.com|NI 9225 Operating Instructions and Specifications
0.50.4
Page 15
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 9225
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 9225 Data Rates
The frequency of a master timebase (fM) controls the data rate (fs)
of the NI 9225. The NI 9225 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 9225 with other modules that use
master timebases to control sampling, all of the modules must
share a single master timebase source. Refer to the software help
f
M
256÷
n
-------------------- -
for information about configuring the master timebase source for
the NI 9225. Visit ni.com/info and enter cseriesdoc for
information about C Series documentation.
The following equation provides the available data rates of the
NI 9225:
=
f
s
where n is 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 9225 has a different set of data rates.
NoteThe cRIO-9151 R Series Expansion chassis does
not support sharing timebases between modules.
16|ni.com|NI 9225 Operating Instructions and Specifications
Page 17
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.
The following specifications are typical for the range -40 to 70 °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
Withstand.................................... 2,300 V
, verified by a 5 s
rms
dielectric withstand test
Channel-to-earth ground
Continuous .................................300 V
, Measurement
rms
Category II
Withstand.................................... 2,300 V
, verified by a 5 s
rms
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.
CautionDo not connect the NI 9225 to signals or use
for measurements within Measurement Categories III or
IV.
24|ni.com|NI 9225 Operating Instructions and Specifications
Page 25
Safety Standards
This product is designed to meet the requirements of the following
standards of safety for electrical equipment for measurement,
control, and laboratory use:
•IEC 61010-1, EN 61010-1
•UL 61010-1, CSA 61010-1
NoteFor UL and other safety certifications, refer to the
product label or visit
ni.com/certification, search
for the module number or product line, and click the
appropriate link in the Certification column.
Hazardous Locations
U.S. (UL) .......................................... Class I, Division 2,
Groups A, B, C, D, T4;
Class I, Zone 2,
AEx nA IIC T4
Canada (C-UL) ................................. Class I, Division 2,
Groups A, B, C, D, T4;
Class I, Zone 2,
Ex nA IIC T4
National Instruments C Series modules are intended for indoor use
only but may be used outdoors if installed in a suitable enclosure.
Refer to the manual for the chassis you are using for more
information about meeting these specifications.
Operating temperature
(IEC 60068-2-1, IEC 60068-2-2) .....-40 to 70 °C
Storage temperature
(IEC 60068-2-1, IEC 60068-2-2) .....-40 to 85 °C
Ingress protection.............................. IP 40
Operating humidity
(IEC 60068-2-56).............................. 10 to 90% RH,
noncondensing
Storage humidity
(IEC 60068-2-56).............................. 5 to 95% RH,
noncondensing
Maximum altitude............................. 2,000 m
Pollution Degree (IEC 60664)..........2
26|ni.com|NI 9225 Operating Instructions and Specifications
Page 27
Shock and Vibration
To meet these specifications, you must panel mount the system and
either affix ferrules to the ends of the terminal wires or use the
NI 9971 backshell kit to protect the connections.
Operating vibration
Random (IEC 60068-2-64)......... 5 g
, 10 to 500 Hz
rms
Sinusoidal (IEC 60068-2-6) ....... 5 g, 10 to 500 Hz
Operating shock
(IEC 60068-2-27).............................. 30 g, 11 ms half sine,
50 g, 3 ms half sine,
18 shocks at 6 orientations
Electromagnetic Compatibility
This product is designed to meet the requirements of the following
standards of EMC for electrical equipment for measurement,
control, and laboratory use:
•EN 61326 EMC requirements; Industrial Immunity
•EN 55011 Emissions; Group 1, Class A
•CE, C-Tick, ICES, and FCC Part 15 Emissions; Class A
NoteRefer to the Declaration of Conformity (DoC) for
this product for any additional regulatory compliance
information. To obtain 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.
Environmental Management
NI is committed to designing and manufacturing products in an
environmentally responsible manner. NI recognizes that
eliminating certain hazardous substances from our products is
beneficial to the environment and to NI customers.
28|ni.com|NI 9225 Operating Instructions and Specifications
Page 29
For additional environmental information, refer to the Minimize
RoHS
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(For information
about China RoHS compliance, go to
ni.com/
environment/rohs_china
.)
Our Environmental Impact web page at
ni.com/environment.
This page contains the environmental regulations and directives
with which NI complies, as well as other environmental
information not included in this document.
Waste Electrical and Electronic Equipment (WEEE)
EU CustomersAt the end of the product life cycle,
all products must be sent to a WEEE recycling center.
For more information about WEEE recycling centers,
National Instruments WEEE initiatives, and compliance
with WEEE Directive 2002/96/EC on Waste and
Electronic Equipment, visit
You can obtain the calibration certificate and information about
calibration services for the NI 9225 at
ni.com/calibration.
Calibration interval ........................... 1 year
Worldwide Support and Services
The National Instruments website is your complete resource for
technical support. At
everything from troubleshooting and application development
self-help resources to email and phone assistance from
NI Application Engineers.
Visit
ni.com/services for NI Factory Installation Services,
repairs, extended warranty, and other services.
Visit
ni.com/register to register your National Instruments
ni.com/support you have access to
product. Product registration facilitates technical support and
ensures that you receive important information updates from NI.
A Declaration of Conformity (DoC) is our claim of compliance
with the Council of the European Communities using the
manufacturer’s declaration of conformity. This system affords the
user protection for electromagnetic compatibility (EMC) and
30|ni.com|NI 9225 Operating Instructions and Specifications
Page 31
product safety. You can obtain the DoC for your product by visiting
ni.com/certification. If your product supports calibration,
you can obtain the calibration certificate for your product
at ni.com/calibration.
National Instruments corporate headquarters is located at
11500 North Mopac Expressway, Austin, Texas, 78759-3504.
National Instruments also has offices located around the world. For
telephone support in the United States, create your service request
at
ni.com/support or dial 1 866 ASK MYNI (275 6964). For
telephone support outside the United States, visit the Worldwide
Offices section of ni.com/niglobal to access the branch office
websites, which provide up-to-date contact information, support
phone numbers, email addresses, and current events.
Refer to the NI Trademarks and Logo Guidelines at ni.com/trademarks for more information on National
Instruments trademarks. Other product and company names mentioned herein are trademarks or trade names of
their respective companies. For patents covering National Instruments products/technology, refer to the appropriate
location: Help»Patents in your software, the Notice at
third-party legal notices in the readme file for your NI product. Refer to the Export Compliance Information at
ni.com/patents. You can find information about end-user license agreements (EULAs) and
patents.txt file on your media, or the National Instruments Patent
ni.com/legal/export-compliance for the National Instruments global trade compliance policy and
how to obtain relevant HTS codes, ECCNs, and other import/export data. NI MAKES NO EXPRESS OR IMPLIED
WARRANTIES AS TO THE ACCURACY OF THE INFORMATION CONTAINED HEREIN AND SHALL NOT BE LIABLE FOR
ANY ERRORS. U.S. Government Customers: The data contained in this manual was developed at private expense
and is subject to the applicable limited rights and restricted data rights as set forth in FAR 52.227-14,
DFAR 252.227-7014, and DFAR 252.227-7015.