Web Sensing

Sensors that use the IEEE 1451 standard are starting to appear, simplifying setup in a wide variety of applications. Users are now taking two approaches for system architectures, using either PC controls or linking sensor subsystems to networks and the Internet.

The Transducer Electronic Data Sheet (TEDS), as 1451 is sometimes called, provides data that until recently had to be hand entered from data sheets. PC-based 1451 systems have gotten much attention, with support from companies such as National Instruments of Austin, TX. NI, has driven the development of the plug-and-play specification for 1451 that helps simplify integration. These systems make it much quicker to set up test applications that have several sensors, providing calibration and minimizing the chance that sensors can be wired incorrectly.

However, many applications don't need the horsepower of PCs, nor can they afford their size or cost. Engineers developing dedicated data acquisition systems such as monitoring temperature in a building or monitoring motion at a secure site can often save money by linking directly to networks. "You can take a small unit with a small, dedicated micro-controller and put the information onto your corporate network, or even onto the Internet," says Jamie Wiczer, president of Sensor Synergy of Buffalo Grove, IL.

Wiczer, who chairs one of the IEEE 1451 standard committees, thinks that this approach provides big benefits in applications that don't need a lot of speed or data storage capabilities. "We had a company that put a sensor in a server room, monitoring temperature. When it rose above 95 degrees overnight, the system sent a text message to the manager's cell phone. He was able to call building maintenance and have the problem resolved," Wiczer says.

Setup times for custom applications can often be fairly quick, since the sensor system has limited functionality. Small footprints and low power requirements make the technique viable for use in building monitoring, from indoor temperature to external motion sensors. These sensors can also be installed on buildings and bridges to monitor stress on suspect joints, sending data over wireless links.

Sensor Synergy is now shipping a module that includes all the software needed to send data over the Internet. The Network Enabled Equipment Monitor the company manufactures can be integrated with many common analog sensors.

Though Wiczer is certainly a big proponent of Web-enabled sensors, he tells Design News that they don't have the speed or diverse functionality of PC-based sensors. "If you're checking data often or sending lots of data in say a video application, the PC systems might work better," Wiczer says.