bout a year and a half ago, we reviewed the status of IEEE P1451.4-compliant sensor developments. The promise of sensors that adhere to the standard is an easier-to-configure device that moves beyond the well-intended but overly complex IEEE P1451.2 specification that, being the first to introduce the concept of transducer electronic data sheets (TEDS), preceded this stage of development.
It seems time to get caught up and see how the promise is shaping up.
"The standard was approved in March by the IEEE standards committee, conditional upon some licensing details being worked out before the next IEEE review meeting in May," reports Joe Pearson, market development manager at National Instruments, and actively involved in NI's Plug & Play Program.
Martin Armson, marketing director at Honeywell Sensotec, provides a quick review of the technology. "Plug-and-play is a data acquisition technology that can simplify the configuration of automated measuring systems by making a sensor's unique identification data available electronically," he reports. "As implemented according to IEEE P1451.4, data in the form of a TEDS is burned on an electrically erasable programmable read-only memory (EEPROM) chip located on the sensor, so when a properly adapted signal conditioner interrogates the sensor, it can interpret the self-identification data."
This eliminates the need for paper calibration sheets. In addition, it can simplify labeling and cabling problems, as well as inventory control issues, by letting the user write location data onto the chip when installing a sensor. "Because all sensors produced according to the standard will carry the same basic, identically formatted, self-identification information, you will be able to mix and match sensors and applicable signal conditioners across manufacturers," adds Armson. Even before its acquisition by Honeywell early in 2003, Sensotec was a participant with NI in P1451 plug-and-play initiatives.
The IEEE P1451.4 standard does not create actual specifications for sensor connectors. Honeywell Sensotec and other key sensor manufacturers are working with National Instruments to address connectivity. "A DB-9 or 10-pin RJ50 or modular-jack connector is expected to become the industry standard," reports Armson. "NI has chosen this on initial products, and it may become a standard, but BNCs are the de facto standard with IEPE transducers. NI beta tested the BNC 2096 TEDS interface module, which it demonstrated at NIWeek 2003, and likely will release a specification soon.
"Moreover, adds Armson, "pin assignments are not standardized at this time. National Instruments and leading sensor manufacturers, including Honeywell Sensotec, hope to make them part of the specification at a later date."
Pearson reports that there now are 22 sensor companies in the Partners Program. The last one to join was Kyowa--the program's first Asian partner.
"NI held a very successful TEDS "plugfest" with 14 sensor partners on March 10th in Austin to make sure the forthcoming smart TEDS sensors work correctly with our soon-to-be-released hardware and software," adds Pearson. "NI recently announced hardware and software products that integrate IEEE 1451.4 TEDS functionality."
So it appears that the significance of this is that TEDS will, for the first time, be available for a wide range of sensor types and measurements.
"A new logo, "Sensors Plug & Play" will be used by many manufacturers who make use of the functionality in the TEDS library for LabView (based on the passed version of the standard) to program their smart TEDS sensors," adds Pearson. "This is important because it conveys interoperability between smart TEDS sensors, software and instrumentation."
Developed in the late '40s as a miniature version of the Type C connector, BNC stands for Bayonet Neill Concelman and, say the folks at Amphenol, is named after Amphenol engineer Carl Concelman. It's also identified as a British Naval Connector or Bayonet Nut Connector.