Design and development of a high precision thermocouple based smart industrial thermometer with on line linearisation and data logging feature

Design and development of a high precision thermometer for industrial application is described in this paper. A class-1 grade K-type Thermocouple is considered for this purpose. The conditioned signal is linearised using a 9th order polynomial based on National Institute of Standards and Technology (NIST) data with the help of a 12-bit analog-to-digital converter and a 8-bit microcontroller. The cold junction compensation is achieved using a serial synchronous temperature to digital converter. The linearised data is transmitted for remote monitoring and logging via RS232C. The system is calibrated with 20 calibration point from 0 °C to 200 °C with a low cost calibration setup. The precision index of the system is also calculated.