DA & Control

Web Tags Leverage RFID and the Internet

February 16, 2010

The low-power wireless tags collect data, digitize them, and communicate them wirelessly to the Internet to create an "instrumentation cloud" in which measurement data are available for use by Web-enabled applications.

AUSTIN, TX -- With its Tag4M WiFi sensor tag, Cores Electronic is taking advantage of RFID technology as well as the latest developments in Internet technology to introduce a new concept in the way we perform measurement and analysis: the "instrumentation cloud". Decades ago, the first instruments collected and analyzed real-world measurements all in one box; then came instrument front ends that connected to PCs Now we are entering a new era where not only is the wireless hardware freed from the confines of cabling, the software is no longer relegated to a specific PC. Instead, measurement front ends connect to the Internet and a web page becomes the instrument, which users can access from anything that can surf the web including mobile devices such as the iPhone.

The tool that implements this revolutionary concept is the Tag4M, which is remarkable on both the hardware and software fronts. Because it leverages RFID technology, this small, credit-card sized measurement board, also called a "WiFi tag", not only collects analog data and performs digital I/O, it communicates directly with any commercially available WiFi access point (AP) or wireless router. In addition, extremely low power consumption means that, depending on the frequency of wake-up periods, a tag can operate on one 3V CR-123A lithium battery literally for several years. The growing use of RFID technology also results in low cost, with volume prices for the Tag4M WiFi tag dropping as low as $50.

In operation, when a Tag4M initially boots up or waking up after having been in Sleep mode, it searches for and automatically associates with an off-the-shelf 802.11b/g access point. Each Tag4M unit has its own permanent MAC address, and it shares a common SSID (default network name) with the AP so it can transfer data and accept commands from any predetermined web page. Users can also connect the AP to a LAN to operate a Tag4M in Local mode.

Even with its low power consumption, the Tag4M's WiFi radio chip and ceramic antenna spec a range of 50 m indoors and 100 m outdoors. Upon association with an AP, the tag sends digitized sensor data over the Internet for any web-based applications to use. None of the existing measurement methods are set up to do this because at present there is little use for raw sensor data being available on the Internet. But with web-enabled applications starting to emerge, the "instrumentation cloud" scheme presents an enormous opportunity. Our vision is that users will route sensor data packets to dedicated computers located anywhere on the Internet, and they will either use local software or run web-based programs for computation, simulation, modeling, analysis and presentation.

Besides the WiFi link, the tag integrates a temperature sensor and provides 5 voltage/current input channels and 4 digital I/O lines. When transmitting it requires roughly 200 mA, and in sleep mode consumption drops to < 10 µA. This means that if the sleep period between readings/transmissions is 1 s, battery life is 52 hr.; with a sleep period of 500 s, lifetime extends to 2 yr.

"Our WiFi tag heralds of a new way of collecting real-world data where we are throwing off the chains that bind us to specific hardware and software," says company president Marius Ghercioiu. "Most wireless sensor units currently on the market are designed to work in Local mode with a computer running a specific software application. In contrast, we designed the Tag4M to interface with a web page, which can be hosted on any web-enabled hardware, whether in your pocket or across the country. Furthermore, given the advent of web-based applications with a model being Google Docs, everything except the physical I/O will take place on the web — logging measurements into a database, performing analysis or displaying the data, it can all take place independent of specific hardware. In this way, we are starting to think about an 'instrumentation cloud' where not only the sensors but also the logging and analysis and control programs can be anywhere you want them."

The Tag4M WiFi sensor tag is available from stock. Price: $124 in single units with aggressive quantity discounts.

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