Thermocouple type analog quantity input module based on SPARC microcontroller

Abstract

The invention provides a thermocouple type analog quantity input module based on an SPARC architecture microcontroller. The thermocouple type analog quantity input module comprises an analog-to-digital conversion circuit, an optocoupler isolator, a microcontroller, a memory and a bus control circuit. The analog-to-digital conversion circuit is used for converting the electromotive force analog quantity generated by the thermocouple due to the thermoelectric effect into a digital quantity code value; the optocoupler isolator realizes isolation of the analog-to-digital conversion circuit and the microcontroller; the microcontroller is used for converting the digital quantity code value generated by the analog-to-digital converter into thermocouple electromotive force and converting the thermocouple electromotive force into corresponding temperature data according to a thermocouple indexing table or an electromotive force temperature relation calculation formula; the memory is used for storing information such as a thermocouple indexing table or an electromotive force temperature relation calculation formula and channel calibration data; and the bus control circuit is used for outputting the temperature data obtained by conversion through a bus. According to the invention, a plurality of cold junction compensation temperature obtaining modes can be supported, and proper cold junction compensation can be selected according to an application scene so as to satisfy an actual temperature measurement demand.

Description

technical field [0001] The invention belongs to the technical field of industrial process control, and in particular relates to a thermocouple type analog input module. Background technique [0002] A thermocouple, as part of a circuit for measuring temperature using the thermoelectric effect, is a pair of conductors of dissimilar materials connected end to end. The end of the thermocouple connected by different material conductors is the measuring end, which is used to feel the measured temperature. The other end of the thermocouple is the reference junction, and the reference junction of the thermocouple is connected to the measuring device, or connected to the measuring device through a compensation wire. The compensation wire is a pair of wires with insulation layer. There are two types of compensation wires: extension type and compensation type. The nominal chemical composition and thermal electromotive force of the extended compensation wire are the same as those of...

AI Technical Summary

Problems solved by technology

The limitation of this approach is: when the cold junction compensation temperature sensor is not close to the output terminal of the thermocouple compensation wire or the cold junction compensation sensor is disturbed by an unexpected heat source, the cold junction compensation cannot effectively reduce the temperature caused by the thermocouple reference junction or the compensation wire Influence of the deviation of the output from 0°C on the measurement result

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