A smart RTD temperature sensor with a prototype IEEE 1451.2 internet interface

A resistance temperature detector (RTD) with a digital, networked smart sensor signal conditioner was designed and tested. The data format and internal transducer electronic transducer data sheet (TEDS) is compatible with a revised (RS232) version of the IEEE 1451.2 smart sensor interface standard. A network capable application processor (NCAP) which interfaces directly to the Internet via Ethernet (without a PC) was demonstrated. Also a version with a PC (via RS232) was tested. A microprocessor with an internal 24-bit A/D and a ratio-metric circuit configuration allowed measurement and computational resolution to within 2 ppm. The overall data resolution was 0.001°C. An advantage of the digital transfer of data is that resolution is not lost in the transfer process. Data can be viewed by any computer on the Internet through a standard browser either directly or through a service website which periodically polls the sensor and stores the data for later review.