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Calibration of process control temperature transmitter

  • US 5,669,713 A
  • Filed: 09/27/1994
  • Issued: 09/23/1997
  • Est. Priority Date: 09/27/1994
  • Status: Expired due to Term
First Claim
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1. A temperature transmitter in a process control loop, comprising:

  • a terminal block for receiving a temperature calibration input resistance from a temperature sensor thermally coupled to the terminal block for cold junction compensation calibration;

    a cold junction compensation temperature sensor coupled to the terminal block for providing an output related to cold junction temperature of the terminal block;

    A/D conversion circuitry for converting the temperature calibration input resistance and the output related to cold junction temperature into digital values;

    I/O circuitry coupling to the process control loop and sending and receiving information over the loop; and

    microprocessor circuitry coupled to the A/D converter for calculating a calibration value for the cold junction compensation temperature sensor based upon the temperature calibration input resistance and the cold junction temperature measured by the cold junction compensation temperature sensor.

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