Plug-and-Play Sensors

Smart sensors identify themselves and remember calibration data, saving setup time. IEEE P1451.4 defines a sensor with embedded TEDS and a mixed-mode, analog and digital interface. Most sensors put out some sort of analog signal -- a voltage, current, or resistance, that varies in a fixed relationship to a physical parameter. Instrumentation that converts the signal to engineering units must know a few things about what parameters to expect from the sensor. That's because full-scale range, sensitivity, connection schemes, and other factors all vary greatly from one kind of sensor to another. The end result is that it takes some effort to match up sensors with monitoring electronics. This configuration process may be no big deal when there are only a few sensors involved. But it can be problematic when gangs of sensors get wired into multichannel measurement systems. Plug-and-play sensors address the labor involved in connection and configuration. Based on open industry standards, plug-and-play sensors incorporate ways of automatically identifying themselves. Benefits include quicker, more automated system setup; better diagnostics; less downtime for sensor repair and replacement; and an easier time keeping track of sensors themselves as well as the data they generate. Two factors have promoted widespread adoption of plug-and-play sensors: the IEEE P1451.4 Smart Transducer Interface draft standard and the Internet. IEEE P1451.4 is a proposed standard for self-describing analog sensors using standardized Transducer Electronic Data Sheets (TEDS). The Internet can bring the plug-and-play concept to legacy sensors and systems via distribution of so-called virtual TEDS. The next generation of measurement and automation systems will use these concepts to become even more automated, robust, and smarter. The 1451 standard itself has been around since the early 90s. The IEEE P1451.2 standard was issued in 1997, and that's when the term TEDS first started to circulate. The first three