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 IEEE1451.2 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 0.001degreesC. 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.