Common Sense Takes Hold

Faster: TEDS provide data that speeds calibration, dramatically speeding setup of multi-sensor systems.

Slowly but surely, standards are starting to take hold in a key technology that links digital controls to the real world: sensors. The IEEE 1451 specification is making inroads in test and measurement, LIN is emerging in automotive applications, and the Zigbee wireless specification is gaining traction.

Sensors are extremely diverse, with many technologies and a multitude of diverse applications. That's made it difficult to find common traits that can be standardized, so sensors haven't seen the cost reductions and ease of integration found in some areas that adopt standards.

But that's beginning to change. The Zigbee wireless network is the newest sensor standard, and it might have the hottest growth at present. The Zigbee Alliance, the technology's trade group, added 27 members in the spring, sending membership beyond 70. In July, the group successfully networked several sensors, proving the scalability of the standard. Wireless links make it possible to automate HVAC controls without wiring, and it can also be used for security on buildings, bridges, and other infrastructures.

In the test and measurement world, the 1451 standard is moving forward after a decade in development. The Transducer Electronic Data Sheet (TEDS) holds setup information, minimizing the challenge of calibrating sensors by hand. That's particularly important in test applications in aerospace, automotive, and other fields that use scores or even hundreds of sensors for a single test. "TEDS enables another layer of automation so people can get tests finished quicker and easier," says Michael Lally, president of The Modal Shop Inc., a Cincinnati, OH sister company of sensor maker PCB Piezotronics.

TEDS isn't expected to have a major role in volume production runs, since the memory that holds calibration information and other data adds cost to a part. But a feature called Virtual TEDS lets users go to corporate websites to get documentation and other information needed for sensor setup and testing.

"With Virtual TEDS, all you need is the serial number of the sensor to get the information you need. There doesn't have to be memory on the sensor," says Brian Betts, Data Acquisition Products Marketing Manager at National Instruments of Austin, TX (www.ni.com).

Though costs will limit TEDS to testing in the auto industry, the largest market for sensors, that industry is slowly inching towards standards. In-vehicle sensors are starting to employ the Local Interconnect Network (LIN), a low-speed bus that can connect sensors in doors.