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General
What is wireless data acquisition?
Wireless data acquisition is an extension of PC-based data acquisition to measurement applications where cables are inconvenient or impractical. NI Wi-Fi data acquisition (DAQ) devices combine IEEE 802.11 wireless technology, Ethernet communication, direct sensor connectivity, and the flexibility of NI LabVIEW software for remote monitoring and control of electrical, physical, mechanical, and acoustic signals. NI Wi-Fi DAQ introduces two new carriers for NI C Series measurement and control modules. The NI WLS-9163 is a single module C Series carrier that delivers IEEE 802.11b/g and Ethernet connectivity back to a host PC, while the NI ENET-9163 is a single module carrier with only Ethernet connectivity. C Series modules offer direct sensor connections and built-in signal conditioning for a variety of measurements, including temperature, strain, high-voltage digital I/O, acceleration, current, and voltage. You can use C Series modules interchangeably for a variety of measurement and control applications across several platforms, including NI CompactDAQ and CompactRIO as well as the NI USB-9162 single module carrier and ENET-9163 Ethernet carrier. You may purchase WLS-9163 carriers and C Series modules separately or together as WLS-9xxx devices.
Figure 1. Each NI Wi-Fi DAQ device combines an NI WLS-9163 carrier and an NI C Series module to provide wireless sensor measurements.
What is the difference between wireless data acquisition and a wireless sensor node?
Unlike most wireless sensors or wireless sensor networks, wireless data acquisition devices are meant to stream data continuously back to a host PC or laptop. A wireless sensor node is typically a low-power, autonomous battery-operated device intended for long-term deployment in applications where measurements are needed only every few minutes, hours, or even days. Wi-Fi data acquisition devices, on the other hand, behave in much the same way as a USB data acquisition device – a host PC collects data continuously (in real time) as the device acquires it. The data acquisition device may be battery-operated, but the focus is on the measurement versus the battery life. Also, Wi-Fi data acquisition devices use the near-ubiquitous wireless networking standard, IEEE 802.11, instead of ZigBee or other IEEE 802.15.4 variants because of its higher bandwidth and broader applicability. Finally, because NI Wi-Fi data acquisition uses the same NI-DAQmx driver software as other NI data acquisition devices, you can develop your applications using NI LabVIEW; LabWindows™/CVI; ANSI C/C++; or Microsoft C#, Visual Basic, or Visual Basic .NET.
What are the NI Wi-Fi DAQ device features?
Each NI Wi-Fi and Ethernet DAQ device can hold one NI C Series measurement module. The measurements, features, and specifications are defined by the type of C Series module in the WLS-9163 or ENET-9163 carrier. A standard 802.11b/g radio or IEEE 802.3 10/100 Mbps Ethernet connection provides connectivity to a host PC. In addition, two digital programmable function interface PFI lines on the back of each device offer timing and synchronization capabilities (such as trigger and clock sharing) with other devices or external events.
Figure 2. NI WLS-9163 Rear Carrier Interface
| 1. RJ45 Ethernet port | 4.Trigger connector |
| 2. LEDs: WLS LINK, ACTIVE, | 5. 10/100 LED |
| STATUS, and POWER | 6. LINK/ACT LED |
| 3. Reset button | 7. Power connector |
Which NI C Series modules work with NI Wi-Fi DAQ hardware?
The following modules work with the NI Wi-Fi DAQ carrier:
| Module | Signal | Channels | Rate | Connectivity |
|---|---|---|---|---|
| Analog Input | ||||
| NI WLS-9211 | Thermocouple, 24-bit | 4 | 14 S/s | Screw terminal |
| NI WLS-9215 | Simultaneous sampling, 16-bit | 4 | 100 kS/s/ch | Screw terminal or BNC |
| NI WLS-9219 | Universal (11 modes) | 4 | 100 S/s/ch | Spring terminal |
| NI WLS-9234 | IEPE (accelerometer and microphone), 24-bit | 4 | 51.2 kS/s/ch | BNC |
| NI WLS-9237 | Bridge completion, 24-bit | 4 | 50 kS/s/ch | RJ50 |
| Digital I/O | ||||
| NI WLS-9421 | 11 to 30 VDC sinking digital input | 8 | Software-timed | Screw terminal or D-Sub |
| NI WLS-9472 | 6 to 30 VDC sourcing digital output | 8 | Software-timed | Screw terminal or D-Sub |
| NI WLS-9481 | 60 VDC, 250 Vrms relay output | 4 | Software-timed | Screw terminal |
Table 1. NI Wi-Fi DAQ Devices
View details, specs, and pricing for modules »
View all C Series modules »
What kind of power does NI Wi-Fi DAQ require?
NI Wi-Fi and Ethernet DAQ devices are DC-powered and are compatible with 9 to 30 VDC power supplies. You may use the 12 VDC power supply included in each shipping kit to power the device or you may wire any 9 to 30 VDC power to a device using the power supply screw terminal connector kit (part number 780702-01). The maximum required input power for a WLS-9xxx device is 4.5 W, though typical continuous power requirements are lower. For example, with a 12 VDC power supply, the continuous current draw for a WLS-9xxx device is typically between 250 and 350 mA, depending on which module you use with the carrier.
Many battery combinations are also possible with different capacities and voltage levels. For instance, a stack of eight 1.5 V AA 2400 mAh NiMH rechargeable batteries typically provides between 6.5 and 9.5 hours of continuous operation for the example above. Lithium Ion-based universal laptop batteries can provide longer run times. When using an off-the-shelf battery, you can order the power supply screw terminal connector kit (part number 780702-01) to connect the battery leads to the WLS-9163.
Learn how to select the right size battery for your application »
How do I connect to an NI Wi-Fi DAQ device?
When setting up your NI Wi-Fi DAQ device, you may choose to connect to an existing enterprise network through a wireless access point or set up your own network with a wireless router. For existing IT infrastructure, NI Wi-Fi DAQ devices support WPA Enterprise and WPA2 Enterprise (IEEE 802.11i). If you set up your own network, you may use WEP, WPA Personal (WPA-PSK), or WPA2 Personal (WPA2-PSK) security. NI Wi-Fi DAQ devices also support ad hoc or peer-to-peer networks, which do not require any routers or access points. However, ad hoc support is inconsistent across wireless network interface cards and is not secure. Communication through a wireless access point or wireless router is the preferred mode of operation.
Learn how to connect through an ad hoc network here »
What is included in each shipping kit?
Every shipping kit for WLS-9xxx wireless data acquisition devices includes the following:
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Performance
How fast can I acquire data?
The rate at which you can acquire data is limited by two factors: the type of C Series module you use in your WLS-9163 or ENET-9163 carrier and your RF environment. Currently, the fastest supported C Series module is the NI 9215, which can acquire up to 100 kS/s simultaneously on each of its four channels. Both carriers support the full rate of this and other C Series modules.
The quality of your RF environment can also impact your maximum data rate. Possible sources of signal interference include other Wi-Fi access points, laptops, cordless phones, and microwaves. IEEE 802.11 defines up to 14 different channels (depending on your region of the world) to avoid network interference. Choosing an open 802.11 channel can dramatically improve performance.
Learn more about optimizing your wireless network »
How many NI Wi-Fi DAQ devices can I use at once?
The number of devices you may use in an NI Wi-Fi DAQ system is ultimately limited by the IEEE Standard 802.11g specification and the bandwidth available in your wireless network/environment. Consider the following four factors when determining how many NI Wi-Fi DAQ devices you can place in your system: acquisition rate, measurement type, number of channels, and the RF environment. The faster you acquire data, the more TCP/IP packets your device must transfer back to a wireless access point or host PC. The same is true of a higher-resolution measurement or more measurement channels – some C Series modules provide 16 bits of resolution while others offer up to 24 bits. Finally, the theoretical bandwidth of 802.11g is 54 Mbps, though there are some practical limitations that keep this specification closer to 24 Mbps. For example, streaming data from three WLS-9234 24-bit measurement devices on all four channels at the full 51.2 kS/s rate requires approximately 19.5 Mbps. One clear IEEE 802.11 channel can accommodate this traffic in a clean RF environment. By lowering the sample rate or adding another access point on a different 802.11 channel, you can add more devices.
What is the range of an NI Wi-Fi DAQ device?
The range and performance of wireless data acquisition devices is derived from the IEEE Standard 802.11 specifications. Typically, you can expect a 30 m range in an office-like environment, where obstructions such as walls and equipment can degrade RF transmissions. With line-of-sight or outdoor environments, a 100 m transmission is possible. Note that at longer distances, your maximum sustainable acquisition rate may decrease. These ranges are guidelines and can vary significantly depending on your wireless router, antenna, and physical obstructions. To extend the range of your wireless network, you may use additional access points, routers with high-gain antennae, or wireless repeaters. Some vendors certify their routers and access points for use with high-gain or directional antennae. Wireless emitters and antennae must be certified together to comply with FCC Rules, Part 15. Many off-the-shelf wireless routers, including the NI WAP-3701, can also function as repeaters to effectively double the range of your Wi-Fi network.
Learn more about IEEE 802.11 range versus throughput »
Which synchronization capabilities are available with NI Wi-Fi DAQ?
Two digital PFI lines on each NI Wi-Fi or Ethernet DAQ device provide start, pause, and reference triggers. They also offer the capability to import or export a sample clock for synchronizing your measurements with other data acquisition devices or external events.
Download NI Wi-Fi DAQ synchronization example code »
What is isolation?
Most C Series modules (including those that work with NI Wi-Fi and Ethernet DAQ hardware) offer isolation as a means of improving the quality and safety of your measurements.
Isolation electrically and physically separates sensor signals, which can be exposed to high-voltage transients and noise, from the measurement system’s low-voltage backplane. Isolation offers many benefits include the following:
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For more information on isolation, refer to the NI Developer Zone Tutorial: Isolation Technologies for Reliable Industrial Measurements.
Security
What security features are available with NI Wi-Fi DAQ?
NI Wi-Fi DAQ devices implement the highest commercially available wireless network security standard, IEEE 802.11i (commonly known as WPA2 Enterprise), including network authentication and data encryption. Authentication ensures that only authorized devices have network access, and encryption prevents data packets from being intercepted. IEEE 802.11 security standards build on more than 10 years of use in the IT sector, and are widely adopted worldwide. By using standard security protocols, NI Wi-Fi DAQ devices make it easy to add wireless measurements to existing IT networks safely.
What is 128-bit AES encryption?
The Advanced Encryption Standard (AES) was chosen by the IEEE 802.11i task group as the preferred encryption algorithm for securing data transmissions over Wi-Fi networks. AES uses a 128-bit cipher that is significantly more difficult to crack than the RC4 algorithm used by older Temporal Key Integrity Protocol (TKIP) and Wired Equivalent Privacy (WEP) encryption standards. In fact, the National Institute of Standards and Technology (NIST) chose AES as the encryption standard recommended for all U.S. government agencies. (FIPS publication 197 describes these requirements in detail.) Any wireless data acquisition application for the government or military likely has to use AES to transmit data.
What is authentication?
Network authentication is essentially client access control. Before a client (such as an NI Wi-Fi DAQ device) can communicate with a wireless access point it must authenticate with the network. There are two basic forms of authentication: server-based and preshared key-based. Most enterprise networks have at least one authentication server, usually running Remote Authentication Dial-In User Service (RADIUS). IEEE 802.11i (WPA2) networks make use of the IEEE 802.1X port-based authentication standard and the Extensible Authentication Protocol (EAP) to control access. NI Wi-Fi DAQ devices support several EAP methods, including LEAP, PEAP, EAP-TLS, and EAP-TTLS. You can also use a pre-shared key if you do not have an authentication server on your network.
Read more about Wi-Fi network security »
Software
How do I program NI Wi-Fi DAQ devices?
All NI Wi-Fi and Ethernet DAQ devices use the same NI-DAQmx measurement services and driver software as other National Instruments PCI, PXI, and USB DAQ devices. NI-DAQmx measurement services software controls every aspect of your data acquisition system from configuration to programming. With NI-DAQmx software, you can quickly configure and acquire measurements using the DAQ Assistant and automatically generate code to get your application started quickly. NI-DAQmx also features virtual channels that automatically scale raw data into engineering units. Because you can use the same driver API to program new NI Wi-Fi DAQ devices, incorporating wireless connectivity into your existing applications is easy.
Which software is included with NI Wi-Fi DAQ devices?
In addition to NI-DAQmx driver software, all NI Wi-Fi and Ethernet DAQ devices include Measurement & Automation Explorer (MAX) configuration software and LabVIEW SignalExpress LE data-logging software. You can use MAX to quickly configure and test your Wi-Fi and Ethernet devices without developing any code. LabVIEW SignalExpress is an interactive, measurement software tool for quickly acquiring, analyzing, and presenting data from hundreds of data acquisition devices and instruments, with no programming required. To learn more about LabVIEW SignalExpress LE, visit ni.com/labview/signalexpress.
Which application development environments (ADEs) work with NI Wi-Fi DAQ devices?
NI Wi-Fi and Ethernet DAQ devices work with development environments compatible with NI-DAQmx, including the following:
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1NI Wi-Fi and Ethernet DAQ devices are not supported by LabVIEW Real-Time Module software.
Test-drive LabVIEW software »
Download the LabVIEW SignalExpress 30-Day evaluation »
Download Measurement Studio evaluation software »
Services and Support
How do I get technical support for NI Wi-Fi DAQ devices?
NI offers extensive support options through ni.com/support. You can call, e-mail, or troubleshoot problems online with NI engineers. In addition, ni.com provides a wealth of resources for every customer – from users getting started with NI Wi-Fi DAQ to experts looking for tips from the designers. Online resources include the following:
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What kind of warranty is provided with NI Wi-Fi DAQ devices?
All NI Wi-Fi and Ethernet DAQ devices have a one-year warranty that covers defects in workmanship and material from the date of product shipment. You can use NI extended warranty options to fix your maintenance costs over two or more years. Contact your NI sales representative for more information.
Additional Resources
Watch the NI Wi-Fi DAQ Guided Tour »
View the Simplify Remote Monitoring with NI LabVIEW Webcast »
View more wireless data acquisition resources »
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