Five actual and proposed standards make up the IEEE 1451 family. Work on this standard began back in 1994 under the direction of Kang Lee of the Sensor Development and Application Group at the National Institute of Standards and Technology, or NIST (www.nist.gov). These interoperable standards are explained and depicted below (see the figure).
IEEE 1451.1 Standard: Issued in 1999, it defines a common object model for the components of a smart transducer and the networks that connect the transducers to the outside world. The model defines a network-capable application processor (NCAP).
IEEE 1451.2 Standard: Issued in 1997, it specifies a transducer-to-microprocessor protocol and a transducer electronic data sheet (TEDS) format for digital point-to-point communications.
PIEEE 1451.3 Proposed Standard: It defines a multidrop configuration for networking distributed transducers with TEDS. As of December 2002, it was undergoing balloting and may already be a standard by the time this article appears in print.
PIEEE 1451.4 Proposed Standard: It defines a mixed-mode interface that allows both digital signals (from the TEDS) and analog signals (from the sensor) to share the same set of wires between the NCAP and the transducer. Balloting on this proposed standard should occur this year.
PIEEE 1451.5 Proposed Standard: Begun last year, it addresses wireless communications between the NCAP and a transducer with a TEDS.
For details, go to http://ieee1451.nist.gov.