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Field measuring instrument and its abnormality managing method

  • US 5,103,409 A
  • Filed: 01/03/1990
  • Issued: 04/07/1992
  • Est. Priority Date: 01/09/1989
  • Status: Expired due to Term
First Claim
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1. A field measuring instrument disposed in a field location in an industrial plant and connected to a communication device at a central location in the industrial plant via a communication line, wherein the field measuring instrument transmits data to the communication device via the communication line, and wherein the communication device modifies an operational parameter of the field measuring instrument via the communication line, the field measuring instrument comprising:

  • a sensor for measuring a parameter to be measured and for outputting a detection signal representing the measured parameter;

    a processing unit for receiving the detection signal from the sensor and processing the received detection signal, and for executing a self-diagnosis program for detecting an abnormality in the field measuring instrument, the processing unit outputting an abnormality flag when an abnormality is detected;

    a counter for counting a predetermined interval of time and for outputting an interruption signal to the processing unit each time the predetermined interval of time is counted;

    a work memory connected to the processing unit for temporarily storing a total number of interruption signals output by the counter; and

    an EEPROM connected to the processing unit for permanently storing the total number of interruption signals output by the counter, and the abnormality flag output by the processing unit together with the total number of interruption signals output by the counter at the time the abnormality is detected by the processing unit, the EEPROM being initialized by the processing unit before being used for the first time;

    wherein the processing unit sets the total number of interruption signals stored in the work memory and the total number of interruption signals stored in the EEPROM to zero when power is applied to the field measuring instrument and the EEPROM has not yet been initialized, and copies the total number of interruption signals stored in the EEPROM into the work memory when power is applied to the field measuring instrument and the EEPROM has already been initialized;

    wherein the processing unit increments the total number of interruption signals stored in the work memory and stores the incremented total number of interruption signals in the EEPROM each time the counter outputs an interruption signal to the processing unit; and

    wherein the processing unit stores the abnormality flag output by the processing unit in the EEPROM together with the total number of interruption signals stored in the work memory at the time the abnormality is detected by the processing unit.

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