National Instruments NI 9225 User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9225
3-Channel, 300 Vrms, 24-Bit Simultaneous,
Channel-to-Channel Isolated Analog Input Module
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2|ni.com |NI 9225 Operating Instructions and Specifications
This document describes how to use the National Instruments 9225
and includes specifications and pin assignments for the NI 9225.
Note The 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.
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NI 9225 Operating Instructions and Specifications |© National Instruments |3
Safety Guidelines
Operate the NI 9225 only as described in these operating
instructions.
Hot Surface This 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.
Caution Do 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 Vpk or 60 VDC to earth ground.

4|ni.com |NI 9225 Operating Instructions and Specifications
Caution Ensure that hazardous voltage wiring is
performed only by qualified personnel adhering to local
electrical standards.
Caution Do not mix hazardous voltage circuits and
human-accessible circuits on the same module.
Caution Make sure that devices and circuits connected
to the module are properly insulated from human contact.
Caution When module terminals are hazardous voltage
LIVE (>42.4 Vpk/60 VDC), you must ensure that devices
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.

NI 9225 Operating Instructions and Specifications |© National Instruments |5
Figure 1 shows the NI 9971 connector backshell.
Figure 1. NI 9971 Connector Backshell

6|ni.com |NI 9225 Operating Instructions and Specifications
Safety Guidelines for Hazardous Locations
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.
Caution Do not disconnect I/O-side wires or connectors
unless power has been switched off or the area is known
to be nonhazardous.
Caution Do not remove modules unless power has been
switched off or the area is known to be nonhazardous.
Caution Substitution of components may impair
suitability for Class I, Division 2.
Caution For Zone 2 applications, install the system
in an enclosure rated to at least IP 54 as defined by
IEC 60529 and EN 60529.

NI 9225 Operating Instructions and Specifications |© National Instruments |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.
Caution To 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.

8|ni.com |NI 9225 Operating Instructions and Specifications
Connecting the NI 9225
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

NI 9225 Operating Instructions and Specifications |© National Instruments |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.
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 9225.

10 |ni.com |NI 9225 Operating Instructions and Specifications
Refer to Figures 3 and 4 for illustrations of how to connect
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
NI 9225
Signal
Source
AI–
+
–
AI+
NI 9225
Signal
Source
AI–
+
–
AI+