Wireless data acquisition is an extension of PC-based data acquisition to measurement applications where cables are inconvenient or impractical. NI CompactDAQ combines IEEE 802.11 wireless technology and support for over 50 measurement modules with the flexibility of NI LabVIEW software for remote monitoring and control of electrical, physical, mechanical, and acoustic signals. The NI cDAQ-9191 chassis houses a single C Series module and delivers IEEE 802.11b/g and Ethernet connectivity back to a host PC, while the NI cDAQ-9181 provides Ethernet connectivity only. 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 both NI CompactDAQ and CompactRIO.
Figure 1. A Wi-Fi NI CompactDAQ measurement system combines a one-slot chassis and an NI C Series module to provide wireless sensor measurements.
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 Wi-Fi NI CompactDAQ chassis 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 the NI CompactDAQ chassis 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.
Each NI Wi-Fi and Ethernet NI CompactDAQ 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 NI cDAQ-9181 or NI cDAQ-9191 chassis. A standard 802.11b/g radio or IEEE 802.3 10/100 Mbps Ethernet connection provides connectivity to a host PC. Additionally, LEDs on the top of the chassis provide users with key information regarding the strength of the wireless signal - one of the biggest factors in signal streaming bandwidth.
Figure 2. NI cDAQ-9191 chassis provides key user feedback through indicator LEDs located on the chassis
|1. Antenna and Antenna Connector
||5. POWER, STATUS and ACTIVE LEDs
|2. 9-30 VDC Power Connector
||6. Wireless Signal Strength LEDs
|3. Ethernet Connector
||7. Chassis Grounding Screw
|4. Reset Button
||8. Module Slot
The NI cDAQ-9181 and NI cDAQ-9191 support over 50 NI C Series modules with measurements including voltage, current, temperature, force, strain, acceleration and many more.
View all C Series modules »
Wi-Fi and Ethernet NI CompactDAQ chassis 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 these chassis 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 NI cDAQ-9191 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 NI cDAQ-9181 or NI cDAQ-9191.
Learn how to select the right size battery for your application »
When setting up your Wi-Fi NI CompactDAQ chassis, 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, Wi-Fi NI CompactDAQ chassis 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. Wi-Fi NI CompactDAQ chassis 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.
Every shipping kit includes the following:
- NI cDAQ-9191 or NI cDAQ-9181 chassis
- 12 VDC power supply (country-specific power cord not included)
- Omnidirectional antenna, 2.4 GHz, 2 dBi (NI cDAQ-9191 only)
- NI-DAQmx 9.4 (or later) software CDs
- LabVIEW SignalExpress LE data-logging software
- NI cDAQ-9191 or NI cDAQ-9181 Chassis Quick Start