Web tags leverage RFID and the Internet to create an ‘instrumentation cloud’

We are entering a new era of measurement technology where not only is 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 analogue 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 for several years.

In operation, when a Tag4M initially boots-up or wakes-up after having been in Sleep mode, it searches for and automatically associates with an off-the-shelf 802.11b/g AP. 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 the Tag4M's low power consumption, its WiFi radio chip and ceramic antenna specification has a range of 50m indoors and 100m outdoors. Upon association with an AP, the tag sends digitised 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.

Besides the WiFi link, the tag integrates a temperature sensor and provides five voltage/current input channels and four digital I/O lines. When transmitting it requires roughly 200mA and in Sleep mode consumption drops to < 10uA. This means that if the sleep period between readings/transmissions is one second, battery life is 52 hours; with a sleep period of 500 seconds lifetime extends to two years.

Our WiFi tag and Web Page Instrument heralds 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 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, analysis and control programs can be anywhere you want them.

Tag4M is supplied and supported by Adept Scientific in the UK, Ireland, Germany, Scandinavia and the Nordic countries, for more information go to www.adeptscience.com.