What is a wireless sensor network?
A wireless sensor network consists of three main components: gateways, nodes, and software. The NI WSN platform provides options in each of these categories so that you can customize your WSN to meet the unique needs of your application.
Wireless measurement systems can overcome power and network infrastructure limitations and meet new and previously difficult application challenges. They deliver reduced costs and increased flexibility compared to traditional wired measurement systems, and they offer the ability to achieve long-term deployments with reliable, battery-powered devices.
What is the difference between NI Wireless CompactDAQ and NI WSN devices?
NI Wireless CompactDAQ devices combine IEEE 802.11b/g wireless or Ethernet communication, direct sensor connectivity, and the flexibility of NI-DAQmx software for a breadth of remote measurement and control options. Externally powered, NI Wi-Fi DAQ devices can stream continuous waveform data on each channel at more than 50 kS/s and offer the highest commercially available network security (WPA2 Enterprise). These devices are intended for shorter term, high throughput/streaming applications, in which you have a single host connected to your wireless client devices.
NI WSNs deliver low-power measurement nodes that operate for up to three years on 4 AA batteries and can be deployed for long-term, remote operation. The wireless measurement nodes communicate with a central gateway using a protocol based on IEEE 802.15.4 to offer mesh routing capabilities that extend network distance and reliability. NI WSN systems support lower data rates to preserve power, are easily programmed using I/O variables. These devices are intended for longer term, slower speed applications in which you might be interested in monitoring your assets or environment once per minute, hour, or day. NI WSN supports multiple data consumers per client, meaning multiple people can access data from your WSN monitoring system any where, any time.
What are the features of these products?
The measurement nodes each offer four analog input channels and two to four digital channels that you can configure on a per-channel basis for input, sinking output, or sourcing output. Four AA alkaline or lithium batteries can deliver up to a three-year node lifetime. The measurement nodes deliver -40 to 70 °C temperature ranges and industrial shock and vibration ratings, and they communicate via 2.4 GHz IEEE 802.15.4 radios that provide up to 300 m outdoor range with line of sight. The 9 to 30 V externally-powered gateways provides flexible connectivity to Windows or real-time OS controllers.
Which network protocol does the NI WSN devices use?
The proprietary NI WSN protocol is based on IEEE 802.15.4 and ZigBee technology. The IEEE 802.15.4 communication standard defines the Physical and Medium Access Control layers in the networking model, providing communication in three frequency bands including the 2.4 GHz ISM band. ZigBee builds on the 802.15.4 standard with the network and application layers, offering features such as device coordination, reliability through mesh networking topologies, and the functionality to create user-defined profiles that allow for customization and flexibility within the protocol. NI-WSN sits on top of the ZigBee layer and closes the protocol to third-party devices, ensuring network and data reliability.
How is the network configured?
With NI-WSN software, which is included with the NI WSN gateways (or downloaded here), you can easily configure your network in the Measurement & Automation Explorer (MAX) utility. MAX provides an intuitive user interface to add and remove measurement nodes and configure wireless settings. To set up your NI WSN, add your gateway under Remote Systems in MAX and assign measurement nodes to a gateway by entering the node serial number. Upon power-up or reset, the nodes automatically reconnect to the assigned gateway.
You can also use MAX to view all of the nodes in your WSN and their last communication time, battery status, and link quality. In addition, MAX provides an interface to set the ZigBee communication channel, configure the Gateway IP address, wirelessly update firmware on the measurement nodes, and configure a node to act as an end device or mesh router.
If you are using the NI 9792 Programmable WSN Gateway, these operations can also be performed from a web browser.
How do I extract measurement data from the WSN?
NI-WSN software provides seamless LabVIEW integration so that you can quickly and easily extract measurement data from your WSN. After adding aNI WSN gateway to a LabVIEW Project, the nodes configured with the gateway in MAX automatically populate in the LabVIEW Project, giving you instant access to their I/O and properties. Simply drag and drop I/O variables from the LabVIEW Project to a LabVIEW Block Diagram for data extraction, analysis, and presentation.
What are the power requirements for NI WSN devices?
The measurement nodes can operate on four 1.5 V, primary AA alkaline or Lithium cells or an external supply. Some NI WSN nodes support battery back-up, meaning the node will automatically switch over to battery power if external power is lost.
When nodes are configured as routers, they must remain on to send and receive data across the network, and should be powered with an external source.
You can use sources other than wall power, such as solar or vibration energy harvesting, to provide external power.
The WSN-9791 and NI 9792 gateways requires an external 9 to 30 V power supply.