" These standards will change the sensors market," said Janusz Bryzek, president and chief executive officer of Transparent Optical MEMS (Fremont, Calif.). "Suddenly, engineers will have access to controls that they never had access to before. Implementation of sophisticated control loops will be dramatically simplified."

The proposed standards are an extension of existing IEEE-1451 standards, which call for 'Sophisticated control loops get dramatically simplified' an open method of tying sensors to network buses. Under the specifications, sensors would be endowed with enough intelligence to identify themselves and work with any type of industrial bus, including Ethernet, Profibus, DeviceNet or any other proprietary system.

Ultimately, engineers hope that networking of sensors will lead to the ability to easily put data up on the Internet. Engineers can, of course, network their sensors today without need for an open standard. But doing so means depending upon proprietary bus technologies. Therefore, users are tied to vendors not only for the two-wire bus, but for the sensors, controllers and interfaces as well.

Keeping it simple
Under IEEE 1451, however, makers of transducers and other sensors don't need to design their products for compatibility with all of the 60-plus industrial buses now available. Instead, the standard calls for a device known as a network-capable application processor, or NCAP, to serve as an interface between a standard transducer bus and the proprietary network bus. Using the NCAP, transducer manufacturers can design all of their sensors with a standard interface.

"This is a big step forward for the transducer makers," said Lee Eccles, senior principal engineer for flight test at Boeing Commercial Airplane Group (Seattle). "Few of them have the wherewithal to go out and support 50 different buses. This lets them concentrate on their area of expertise rather than on the entire industrial market."

Several big suppliers have joined the effort to back IEEE 1451 and provide standardized technology. Hewlett-Packard Co. (Palo Alto, Calif.) has announced it will make NCAPs. And Analog Devices Inc. (Norwood, Mass.) worked with sensor makers to develop the Microconverter, a 16-MHz, 12-bit and 24-bit microcontroller that serves as the on-board intelligence for smart sensors.

Using the Microconverter, engineers have created standard transducer interface modules that interface with the NCAPs in earlier versions of IEEE 1451.

"Basically, we are dividing the network pie into pieces and letting each company work on its piece of the pie without regard to which network bus is being used," Eccles said. "So the transducer manufacturer no longer needs to know the ins and outs of Profibus. And he doesn't need to develop 50 different modules and 50 different interfaces to go with each of the industrial networks out there."

One of the keys to the success of 1451 standardization, however, is the approval of the P1451.3 and P1451.4 extensions. The first proposed standard would provide higher performance, mostly through greater bandwidth. Standard protocols in P1451.3 call for 50-MHz performance, against about 1 MHz on earlier versions.

Newer systems would also enable multiple sensors to interface with an NCAP through the transducer bus. Advances in 1451.4, meanwhile, would accommodate analog transducers, which in turn would allow users to employ existing plant wiring.

With 1451 technology, engineers say they can vastly simplify the wiring process for any sensor application, and can obtain more accurate results in many situations. Boeing, for example, plans to use 1451-based systems for flight-test applications on Boeing 777 aircraft. By using the new technology on so-called pressure belts, Boeing engineers can measure forces on the top and bottom surfaces of the 777's wings. The pressure belts, designed in conjunction with Endevco Corp. (San Juan Capistrano, Calif.), use transducers at intervals of every 2 inches along their length.

By connecting 2,000 of the those transducers to a network, instead of discretely wiring each of them to multiplexers, Boeing engineers say they can dramatically reduce the thickness of wiring bundles. In past programs, such as on the 747, each sensor was discretely wired back to a multiplexer in the aircraft's fuselage. Doing it that way, the wiring bundles in the 747's wings were often as much as a foot thick. Networking of sensors could reduce the total bundle to about a half-inch in diameter.

"We used to pull the plane into a hangar, take three weeks to instrument it and then take another week for measurements," Eccles said. "Now we expect the whole process to take about one week. And we'll get better data and save tens of thousands of dollars in the process."

The 'Net beckons
Still on the drawing boards are plans to move sensor data onto the Internet. Several companies are preparing for that by developing Web-enabled instruments. Telemonitor Inc. (Columbia, Md.), for example, has introduced Web-enabled transducer interface modules.

"We want to take Internet Protocol to the individual transducers, so that every transducer will be Web-aware," said company president Robert Johnson.

Users believe that Web-enabled sensors could give design engineers a leg up in test applications. "If a senior engineer on the ground wants to know what's happening during flight test, he could use the Internet to interrogate the transducers," Boeing's Eccles said.

Engineers at last week's conference outlined a wide variety of potential applications for 1451 technology, including digital car window sensors, wireless tire pressure sensors, smart highway sensors and wireless medical sensors for patients. They also described a multitude of applications in the industrial automation market.

Some experts believe that the technology offered by IEEE 1451 could change the power balance of the $10 billion-a-year sensor market. "Right now, the majority of the revenues are generated by about 20 percent of the sensor companies," said Bryzek of Transparent Optical MEMS.

"With this standard, a lot of the smaller companies could compete more effectively because they could focus more on the technology once they find the right market niche."

Engineers supporting the two proposed standards said they hope to start the approval process by the end of 2000.