National Instruments WSN-3226 User manual

USER GUIDE AND SPECIFICATIONS
NI WSN-3226
NI Wireless Sensor Network 4-Channel, 20-Bit Voltage/RTD Node
This user guide describes how to use the NI WSN-3226 voltage/RTD node and lists its specifications.
Figure 1 shows the NI WSN system components.
Figure 1. NI WSN System Components
The NI WSN-3226 is a four-channel, low-power, wireless voltage/resistance device that works with
other NI WSN-32xx nodes and gateways to form a wireless sensor network. The NI WSN system
consists of one or more NI WSN gateways, up to 36 NI WSN-32xx nodes per gateway, and multiple PCs
or Programmable Automation Controllers (PACs) to receive and analyze the distributed sensor data. For
more information about PACs, visit ni.com.
When you connect the NI WSN gateway, you can use a separate host PC running Windows, or a PAC
running NI LabVIEW Real-Time, to display measurement results, status information, and to change the
NI WSN gateway and NI WSN-3226 device settings.
1 NI WSN-32xx Nodes
2 NI 9792 WSN Real-Time Gateway
3 NI WSN-9791 Ethernet Gateway
4 PC Running NI Software
4
2
1
1
3
Or

NI WSN-3226 User Guide and Specifications 2 ni.com
Dimensions
Figure 2 shows the NI WSN-3226 device dimensions.
Figure 2. NI WSN-3226 Device Dimensions
Safety Guidelines
Operate the NI WSN-3226 device only as described in this user guide.
Hot Surface This icon denotes that the component may be hot. Touching this component may result
in bodily injury.
NI WSN Safety Information
The following section contains important safety information that you must follow when installing and
using NI WSN products.
Caution Do not operate the NI WSN product in a manner not specified in the user manual or
operating instructions. 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.
Caution Do not substitute parts or modify the NI WSN product. Use the product only with the
devices, accessories, and cables specified in the installation instructions.
Caution Do not operate NI WSN products in an explosive atmosphere or where there may be
flammable gases or fumes.
124 mm
(4.88 in.)
86.4 mm
(3.40 in.)
42.4 mm
(1.67 in.) 50.8 mm
(2.00 in.)
25.40 mm
(1.00 in.)
55.9 mm
(2.20 in.)
235 mm
(9.25 in.)

©National Instruments Corporation 3 NI WSN-3226 User Guide and Specifications
Caution If you need to clean a NI WSN product, wipe it with a dry towel. The product must be
completely dry and free from contaminants before you return it to service.
Caution Operate the product indoors only at or below Pollution Degree 2. Pollution is foreign matter
in a solid, liquid, or gaseous state that can reduce dielectric strength or surface resistivity.
Caution You must insulate signal connections for the maximum voltage for which the NI WSN
product is rated. Do not exceed the maximum ratings for the product. Do not install wiring while the
product is live with electrical signals. Do not remove or add connector blocks when power is
connected to the NI WSN system. Avoid contact between your body and the connector block signal
wiring when hot-swapping devices.
Caution To comply with safety regulations, use only recommended batteries with this product.
Refer to the Battery Power section for the recommended battery types.
Safety Guidelines for Hazardous Locations
The NI WSN-3226 is suitable for use in Class I, Division 2, Groups A, B, C, D, T4 hazardous locations;
Class I, Zone 2, AEx nC IIC T4 and Ex nL IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if you are installing the NI WSN-3226 in a potentially explosive
environment. Not following these guidelines may result in serious injury or death.
Caution Observe the battery manufacturers’ operating temperature ratings listed in the Battery
operating temperature range specification section.
Caution Do not disconnect the power supply wires and connectors from the device unless power has
been switched off.
Caution Do not install or remove the device unless power has been switched off.
Caution Substitution of components may impair suitability for Class I, Division 2.
Caution For Zone 2 applications, install the WSN system in an enclosure rated to at least IP 54 as
defined by IEC 60529 and EN 60529.
Special Conditions for Hazardous Locations Use in Europe
Caution The NI WSN-3226 has been evaluated as Ex nA nL IIC T4 equipment under DEMKO
Certificate No. 07 nA nL 0626664X. Each device is marked II 3G and is suitable for use in Zone 2
hazardous locations, in ambient temperatures of –40 °C ≤Ta ≤70 °C.
Electromagnetic Compatibility Guidelines
This product was tested and complies with the regulatory requirements and limits for electromagnetic
compatibility (EMC) as stated in the product specifications. These requirements and limits are designed
to provide reasonable protection against harmful interference when the product is operated in its
intended operational electromagnetic environment.
This product is intended for use in industrial locations. There is no guarantee that harmful interference
will not occur in a particular installation, when the product is connected to a test object, or if the product
is used in residential areas. To minimize the potential for the product to cause interference to radio and
television reception or to experience unacceptable performance degradation, install and use this product
in strict accordance with the instructions in the product documentation.
Furthermore, any changes or modifications to the product not expressly approved by National
Instruments could void your authority to operate it under your local regulatory rules.

NI WSN-3226 User Guide and Specifications 4 ni.com
The following statements contain important EMC information needed before installing and using this
product:
Caution To ensure the specified EMC performance, product installation requires either special
considerations or user-installed, add-on devices. See the product installation instructions for further
information.
Caution To ensure the specified EMC performance, operate this product only with shielded cables
and accessories.
Caution To ensure the specified EMC performance, operate this product with a DGND terminal on
the I/O connector tied to earth ground or use the NI recommended external power supply
(NI part number 780703-01) or equivalent.
Caution The inputs/outputs of this product can be damaged if subjected to Electrostatic Discharge
(ESD). To prevent damage, industry-standard ESD prevention measures must be employed during
installation, maintenance, and operation.
Caution This product may become more sensitive to electromagnetic disturbances in the operational
environment when test leads are attached or when connected to a test object.
Related Documentation
Check ni.com/manuals for the most recent documentation. For a complete list of documentation
related to the NI WSN system, refer to ni.com/info and enter rdwsnrd.
In addition to this guide, the following documents may be useful when configuring your NI WSN
system:
• NI Wireless Sensor Network Getting Started Guide
• NI WSN-9791 Ethernet Gateway User Guide and Specifications
• NI 9792 WSN Real-Time Gateway User Guide and Specifications
•Configuring WSN in MAX, available from Start»All Programs»National Instruments»NI-WSN
•LabVIEW Help for WSN Devices, available in LabVIEW from Help»LV Help»
WSN Devices Help
•NI-WSN Readme, available on the software installation disc included with your gateway
Training Courses
If you need more help getting started developing an application with NI products, NI offers training
courses. To enroll in a course or obtain a detailed course outline, refer to ni.com/training.
Technical Support on the Web
For additional support, refer to ni.com/support or zone.ni.com.
Software Overview
Note Refer to the NI WSN Readme, available on the software installation disc included with your
gateway, for NI software application version support.
NI-WSN software includes NI Measurement & Automation Explorer (MAX) as well as server and
driver software for easy integration into application software packages. These software components
manage the low-level communications and hardware configurations, simplifying programmatic access
to I/O channels. The NI-WSN software is on the software installation disc included with your NI WSN

©National Instruments Corporation 5 NI WSN-3226 User Guide and Specifications
gateway device. The NI-WSN software is supported by Windows 7/Vista/XP and contains the following
components:
•NIMAX
• NI-WSN
You can download a current version of NI-WSN software from ni.com/support. Using your Web
browser, go to ni.com/support and select Drivers and Updates»Distributed I/O»Wireless Sensor
Networks, and then select the latest version of NI-WSN software. If you are using other software, refer
to the installation instructions that accompany your software.
What You Need to Get Started
To set up and use NI LabVIEW with the NI WSN-3226 device, you need the following:
•NIWSNgateway
• NI WSN-3226 device(s) with a 5–30 V power supply or four alkaline or lithium AA 1.5 V batteries
for each node. Refer to the Battery Power section for recommended battery types.
• Mounting hardware (DIN rail, panel-mount, or rack mount accessory)
• Ethernet cable/connection
• 1/8 in. flathead and number 2 Phillips screwdrivers
• NI-WSN software version 1.2 or later
• Host PC running Windows 7/Vista/XP or LabVIEW Real-Time
• NI LabVIEW 2010 (32-bit) or later
•(NI 9792 WSN Real-Time Gateway Only)—NI LabVIEW 2009 SP1 (32-bit) Real-Time Module or
later
• Related hardware and software documentation
Unpack the Device and Install the Antenna
Remove the device from the package and inspect the device. Contact NI if the device appears damaged.
Do not install a damaged device.
Caution The device is static sensitive. Always properly ground yourself and the equipment when
handling or connecting to the device.
To attach the antenna, align the antenna with the mount and screw it on, as shown in Figure 3.
Caution The antenna must be attached to the NI WSN device in order for the NI WSN device to
function correctly.

NI WSN-3226 User Guide and Specifications 6 ni.com
Figure 3. Attach the Antenna to the Device
Mounting the NI WSN-3226 Device
You can mount the NI WSN-3226 on a panel or on a 35 mm DIN rail. For kit accessory ordering
information, refer to the NI WSN product page accessory section at ni.com. Before using any of these
mounting methods, remove and save the serial number sticker located on the back of the NI WSN-3226
device for future use when configuring your device in software. For the NI WSN-3226 device
dimensions, refer to Figure 2.
Caution Your installation must allow 50.8 mm (2 in.) of clearance in front of devices for common
connector cabling, such as the 18-terminal detachable screw terminal connector.
Attaching the NI WSN-3282 DIN Rail (Optional)
You can mount the NI WSN-3226 on a standard 35 mm DIN rail using a NI WSN-3282 DIN rail clip,
NI part number 781074-01. Complete the following steps to mount the NI WSN-3226 on a DIN rail:
Caution Power off the device before mounting it to the DIN rail.
Note Use thread-forming screws to permanently affix the DIN rail clip to the device. Unscrewing
and reinstalling the thread-forming screws will produce a compromised connection between the DIN
rail clip and the device.
1. Fasten the DIN rail clip to the NI WSN-3226 using a number 2 Phillips screwdriver and the
four 8-32 ×5/16 in. thread-forming screws that shipped with the DIN rail clip(s). Figure 4 shows
how to fasten the DIN rail clip to the NI WSN-3226.
Caution Do not use screws longer than 5/16 in. to fasten the DIN rail clip to the NI WSN-3226.
NATIONAL
INSTRUMENTS
NATIONAL
INSTRUMENTS

©National Instruments Corporation 7 NI WSN-3226 User Guide and Specifications
Figure 4. NI WSN-3226 Device DIN Rail Installation
2. Insert one edge of the DIN rail into the deeper opening of the DIN rail clip, as shown in Figure 5.
Figure 5. DIN Rail Clip Installation
3. Press down firmly on the NI WSN-3226 to compress the spring until the clip locks into place on
the DIN rail.
1 DIN Rail Clip (Without Device) 2 DIN Rail
2
1

NI WSN-3226 User Guide and Specifications 8 ni.com
Using a Panel Mount Accessory
The NI WSN-3280/3281 panel mount accessories, part numbers 780999-01 and 781073-01, each
include a retention clip and knob and integrated strain relief for power and I/O wires. You can use the
NI WSN-3280 panel mount accessory to attach the NI WSN-3226 device to a panel or other flat
surface. The NI WSN-3281 panel mount accessory also includes a magnetic mount for attaching the
NI WSN-3226 device to metallic surfaces. Figure 6 shows the NI WSN-3226 panel mounting
dimensions.
Figure 6. NI WSN-3226 Device Panel Mount Dimensions
78.74 mm
(3.100 in.)
4.5 mm
(5× Ø.177 in.)
44.02 mm
(1.733 in.)
183.79 mm
(7.236 in.)
55.88 mm
(2.200 in.)
13.97 mm
(0.550 in.)
25.40 mm
(1.000 in.)
25.40 mm
(1.000 in.)
53.34 mm
(2.100 in.)

©National Instruments Corporation 9 NI WSN-3226 User Guide and Specifications
Figure 7. Panel Mount Accessory
Refer to Figure 7 while completing the following steps to mount the NI WSN-3226 on a panel:
1. (NI WSN-3280) Bolt or screw the panel mount accessory to a panel using five 8-32 or M4 screws.
(NI WSN-3281) Attach the panel mount accessory using the integrated magnet.
2. Slide the NI WSN-3226 device into the panel mount accessory as shown in Figure 7.
1 Retention Knob
2 Retention Clip
3 Mounting Hole
4 Integrated Mounting Pin
5 Power and I/O Strain Relief
NATIONAL
INSTRUMENTS
1
5
4
2
3
5

NI WSN-3226 User Guide and Specifications 10 ni.com
3. Slide the retention clip down and tighten the panel mount knob to secure the NI WSN-3226 device
as shown in Figure 8.
Figure 8. Slide Retention Clip Down and Tighten Panel Mount Knob
4. (Optional) Secure any I/O signal or power supply cabling to the panel mount accessory using a
zip-tie and the integrated strain relief slots.
NATIONAL
INSTRUMENTS
NATIONAL
INSTRUMENTS

©National Instruments Corporation 11 NI WSN-3226 User Guide and Specifications
Using the Integrated Panel Mount Slots
You can also mount the NI WSN-3226 to a panel using the integrated panel mount slots as shown in
Figure 9.
1. Attach three number 8 or M4 pan head screws in the mounting panel, leaving 0.1 in. space under
the head of each screw. Refer to Figure 2 for the correct hole pattern and dimensions.
2. Slide the NI WSN-3226 device onto the panel.
Note In this configuration, the NI WSN-3226 is held in place only by the weight of the device and
the friction of the screw attachment. Use the DIN rail clip or panel mount accessories in high
vibration environments.
Figure 9. Integrated Panel Mount Slots
Caution Disconnect power before removing the device from the panel.
Setting Up the NI WSN-3226 Device
The following sections discuss setting up the NI WSN-3226 for use.
Installing the Software
You must be an Administrator to install NI software and devices on your computer. Before connecting
the hardware, install the following software in the following order:
1. NI LabVIEW, available at ni.com/support.
2. NI-WSN and NI MAX, which are included on the software installation disc included with your
NI WSN gateway and are also available for download at ni.com/support.
Note After installation of NI-WSN, the NI Wireless Sensor Network Getting Started Guide is
available from Start»All Programs»National Instruments»NI-WSN.

NI WSN-3226 User Guide and Specifications 12 ni.com
Powering the NI WSN-3226 Device
The NI WSN-3226 device can be powered by either an external power supply or four AA alkaline or
lithium batteries. Refer to the Specifications section for details about the input power and battery
requirements.
If both battery and external power are connected, the NI WSN-3226 functions from the external power
input. The device is designed to provide battery backup in the event of loss of external power and will
automatically switch to battery power when external power is lost.
Installing Batteries
To install batteries in the NI WSN-3226 device, complete the following steps:
1. Loosen the battery compartment retention screw and remove the compartment cover, as shown in
Figure 10.
Figure 10. NI WSN-3226 Battery Compartment
Caution Using the incorrect battery type causes an explosion risk. Do not use rechargeable batteries.
Refer to the Battery Replacement and Disposal section for information about how to dispose of used
batteries.
Note When using the NI WSN-3226 device on battery power, you should configure the device as
an end node so that it sleeps most of the time. Running a device configured in router mode from
battery power greatly reduces the battery life. The device ships from the factory configured as an end
node. For more information about how to switch the node from an end node to router mode, refer to
Configuring WSN in MAX, available from Start»All Programs»National Instruments»NI-WSN.
2. Install four AA alkaline or lithium batteries in the device, making sure to install them with the
correct polarity. Figure 12 shows the battery polarity markings inside the device battery
compartment.
3. Reinstall the battery compartment cover and tighten the retention screw.
1 Battery Retention Screw
1

©National Instruments Corporation 13 NI WSN-3226 User Guide and Specifications
Connecting External Power to the NI WSN-3226 Device
To connect an external power supply to the NI WSN-3226, complete the following steps:
1. Remove the 2-position mini-combicon plug from the device. Loosen the retaining screws if
necessary.
Figure 11. 2-Position Mini-Combicon Plug
2. Connect the external power supply positive lead to the V terminal.
3. Connect the negative (common) lead to the C terminal.
4. Reinstall the 2-position mini-combicon plug in the device and tighten the retaining screws.
Caution You must use a UL Listed ITE power supply marked LPS with the NI WSN-3226.
The power supply must also meet any safety and compliance requirements for the country of use.

NI WSN-3226 User Guide and Specifications 14 ni.com
Device Interface
Figure 12 shows the NI WSN-3226 device interface.
Figure 12. NI WSN-3226 Node Interface
1 Antenna
2 WSN Connect Button
3 Signal Strength/Status LEDs
4 User LED
5 Battery Slots/Polarity Indicators
6 I/O Connector
7 Reset Button
8Pro2 Port (Reserved for Future Use)
9 5–30 V External Power Input
1
3
4
6
7
9
2
5
8

©National Instruments Corporation 15 NI WSN-3226 User Guide and Specifications
Signal Strength/Status LED Indicators
The NI WSN-3226 has four signal strength/status LED indicators, which flash twice before displaying
signal strength information. Table 1 shows the status and signal strength LED patterns.
Table 1. Signal Strength and Status LED State/Node Status
LED Indication
Mode LED State LED Pattern Device Status
Signal Strength—
LEDS 1–4 blink
twice and then
display the signal
strength for three
seconds
LED 1–4 OFF Low Signal
LED 1 ON,
LED 2–4 OFF
Poor
LED 1–2 ON,
LED 3–4 OFF
Fair
LED 1–3 ON,
LED 4 OFF
Good
LED 1–4 ON Excellent
Status Indication Each LED 1–4
blinking in
succession
Searching for a network
LED 1, 4 and 2, 3
alternate blinking
Updating firmware
LED 1–4
continuously
blinking
Error. Reboot device. If problem
persists, reset device to factory
default settings. Go to ni.com/
support for additional
troubleshooting steps.
1234
1234
1234
1234
1234
12341234
1234
1234
12341234
12341234

©National Instruments Corporation 16 NI WSN-3226 User Guide and Specifications
WSN Connect Button
Note Refer to your NI WSN gateway documentation for detailed instructions about how to connect
a NI WSN-3226 to the NI WSN gateway.
The NI WSN-3226 is equipped with a WSN connect button as shown in Figure 12. The button controls
network connection and the LEDs, which display connection status.
Pressing the WSN connect button results in the device responses shown in Table 2.
Reset Button
The NI WSN-3226 is equipped with a reset button as shown in Figure 12.
Pressing the reset button results in the following device responses:
• When pressed for fewer than 5 seconds, the device reboots with the current configuration.
• When pressed for 5 seconds or more, the device reboots into Factory Default Mode, which returns
the device user configuration to the factory-set defaults.
Using the NI WSN-3226 Device
Analog Input Circuitry
The NI WSN-3226 supports two modes: voltage and 3-wire resistance/RTD mode. These modes are
selectable per channel. Inputs are sampled with 20 bits of digital resolution, but effective resolution
depends upon noise. The noise varies according to filter settings.
The NI WSN-3226 supports the ability to digitally filter the analog input in order to reject powerline
noise from the measured signal. The node can enable rejection for 50 Hz, 60 Hz, or both frequencies,
making it flexible for different environments where the powerline energy frequency may not be known.
The node can also be programmed in one of two filtering strength modes: low power mode or high
rejection mode. High rejection mode allows for better noise rejection at the expense of higher energy
per measurement consumed by the node. If the powerline noise frequency is known, it is desirable to
configure the filter to reject only that frequency instead of both 50 Hz and 60 Hz, since the latter will
consume more energy per measurement than only 50 Hz or only 60 Hz rejection. When powerline
filtering is disabled, logic in the node still performs filtering, but at higher frequencies. With powerline
filtering disabled, a filtering strength of high rejection is recommended for the best resolution.
Table 2. WSN Connect State/Device Status
Current Device State Duration of Button Press Result
Initial power on,
not connected
Any duration Node turns on and searches for an available network.
Connected to a
NI WSN-9791 or
NI 9792
<5 seconds Node blinks all four signal strength LEDs twice, and
then displays the signal strength as shown in Table 1.
≥5 seconds Node leaves current network and searches for a new
network.

NI WSN-3226 User Guide and Specifications 17 ni.com
Voltage Mode
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 WSN-3226.
In voltage mode, the NI WSN-3226 supports single-ended DC measurements. Each channel has an AI
and a COM terminal to which you can connect a voltage signal. Figure 13 shows the NI WSN-3226
input circuitry in voltage mode. To measure a voltage signal, connect the positive lead to the AI terminal,
and the ground lead to the adjacent COM terminal. Figure 14 shows an example of a single-ended
voltage signal connected to the NI WSN-3226. The COM terminal is internally connected to the ground
reference of the NI WSN-3226. Each channel includes overvoltage protection. Refer to the
Specifications section for more information about overvoltage protection.
.
Figure 13. Input Circuitry for One Channel in Voltage Mode
Figure 14. Connecting a Single-Ended Voltage Signal
Resistance/RTD Mode
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 WSN-3226.
In resistance/RTD mode, the NI WSN-3226 supports 3-wire RTDs. The NI WSN-3226 supports
three ranges:
• Up to 400 Ω for 100 Ohm Platinum (Pt100) RTDs
• Up to 4000 Ωfor 1000 Ohm Platinum (Pt1000) RTDs
• Up to 100 kΩfor thermistors and general-purpose resistors
NI WSN-3226
ADC
COM
AI
MUX
Buffer
Protection
NI WSN-3226
EX
COM
Voltage Source
AI
+
_
NC

NI WSN-3226 User Guide and Specifications 18 ni.com
These ranges are selectable per node; all channels set to resistance/RTD mode are set to the same range.
The node also protects each channel from overvoltages. Refer to the Specifications section for more
information about overvoltage protection. Figure 15 shows the NI WSN-3226 input circuitry in
resistance mode.
Figure 15. Input Circuitry for One Channel in Resistance Mode
There are four RTD channels on the NI WSN-3226. Each channel has three terminals:
• EX terminal—Sources the excitation current. Connect the positive lead of the RTD to this terminal.
• AI terminal—Measures the RTD resistance. Connect the sense lead of the RTD to this terminal.
• COM terminal—Connect the negative lead of the RTD to this terminal.
Figure 16 shows an example of connecting a RTD to the NI WSN-3226.
Figure 16. Connecting a RTD
The NI WSN-3226 sources different current levels on the EX terminal depending on the selected range.
For more information about the current source value for each range, refer to the Specifications section.
The NI WSN-3226 compensates for lead resistance errors. For the best measurement results when
measuring a 3-wire RTD, use equal length wires between the RTD and the EX, AI, and COM terminals.
You should also keep the leads as short as possible.
RTD Types
RTD types are specified by material composition, nominal resistance at 0 °C, and TCR (temperature
coefficient of resistance, or alpha). The NI WSN-3226 can directly measure the temperature of platinum
RTDs of either 100 Ω or 1,000 Ωnominal resistance. These RTDs are commonly referred to as Pt100 or
Pt1000 RTDs, respectively.
NI WSN-3226
ADC
EX
COM
AI
Excitation
Current
Buffer and Lead
Compensation MUX
NI WSN-3226
EX
COM
RTD
AI

©National Instruments Corporation 19 NI WSN-3226 User Guide and Specifications
Different types of platinum RTDs have different TCRs. The NI WSN-3226 supports the following
TCRs: 3750, 3851, 3911, 3916, 3920, and 3928 μΩ/Ω/°C. The most common TCR for RTDs is
3851 μΩ/Ω/°C, as defined in IEC-751, DIN 43760, BS 1904, and ASTM E1137 international standards.
The TCR of 3928 μΩ/Ω/°C is used in the reference function for platinum thermometers in the
International Temperature Scale of 1990 (ITS-90) for high-accuracy metrology applications.
Unfortunately, not all TCR values are as well defined by standards organizations, and the behavior of
RTDs with the same TCR value may vary from vendor to vendor. The variations are usually small. The
built-in linearization algorithms of the NI WSN-3226 are appropriate for nearly all applications.
The NI WSN-3226 uses a linearization curve known as the Callendar-Van Dusen equation to measure
the temperature of RTDs. The equation is as follows:
Temperatures below 0 °C:
RT= R0[1 + A × T+ B × T2+ C ×T3× (T– 100 °C)]
Temperatures above 0 °C:
RT= R0[1 + A ×T+ B ×T2]
where T = temperature in °C
RT= RTD resistance at temperature T
R0= RTD nominal resistance at 0 °C
A, B, C are coefficients given in Table 3
Table 3 lists the coefficients used in this equation for the TCR values that the NI WSN-3226 supports.
If you have a nonstandard RTD that does not match one of these linearization curves, measure the RTD
in the resistance mode of NI WSN-3226, and convert the resistance to temperature in the manner
suggested by the RTD vendor.
Controlling Digital Inputs and Outputs
The following sections discuss how to configure the NI WSN-3226 device for different types of input
and output, and how to connect external devices to the NI WSN-3226 DIO terminals.
On the 18-position screw terminal connector, terminals 13–17 are the DIO section. The DIO section has
the following terminals:
•DIOx—signal terminal
• DGND—ground terminal
• DIO PWR—DIO Power positive (required when one of the DIO channels is configured for Drive
High (Sourcing) or Drive High and Low (Sinking and Sourcing) mode)
Table 3. NI WSN-3226 Callendar-Van Dusen Coefficients
TCR
μΩ /Ω/°C
A
(°C)–1
B
(°C)–2
C
(°C)–4
3750 3.81 ×10–3 –6.02 ×10–7 –6.0 ×10–12
3851 3.9083 ×10–3 –5.775 ×10–7 –4.183 ×10–12
3911 3.9692 ×10–3 –5.8495 ×10–7 –4.233 ×10–12
3916 3.9739 ×10–3 –5.870 ×10–7 –4.4 ×10–12
3920 3.9787 ×10–3 –5.8686 ×10–7 –4.167 ×10–12
3928 3.9888 ×10–3 –5.915 ×10–7 –3.85 ×10–12

NI WSN-3226 User Guide and Specifications 20 ni.com
Note Use the Node Properties dialog box in the LabVIEW Project Explorer window to change
DIO settings.
The NI WSN-3226 device has two bi-directional digital I/O channels. Each channel supports
eight operational modes depending on whether the channel is configured as digital output or digital
input. The NI-WSN software controls the different modes of operation by turning on and off the high
side and low side switches.
Digital Output Operational Modes
The channels support the following digital output operational modes:
•Drive High (Sourcing)
•Drive Low (Sinking)
•3V TTL Logic (Open-Collector with Pull-Up)
•Drive High and Low (Sinking and Sourcing)
Note When configured in a digital output mode, reading the channel returns the state of the pin
voltage with TTL thresholds.
Digital Input Operational Modes
The channels support the following digital input operational modes:
•24V Sinking
•24V Sinking with Power Management
•TTL Logic
•Contact Closure
Figure 17. Simplified Circuit Diagram of One DIO Channel
Connecting Digital Outputs
You can connect a variety of industrial devices such as solenoids, relays, and indicators to the
NI WSN-3226 device. Refer to the Specifications section to ensure compatibility.
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 WSN-3226.
DIO PWR
High Side Switch
TTL
Pull Up
DIOx
3V
DGND
Low Side Switch
DI
(Internal)
NI WSN-3226
24V Sinking
Load