Process variable measurement noise diagnostic
First Claim
1. A process variable transmitter, comprising:
- a process variable sensor configured to sense a process variable of an industrial process and responsively provide a sensor signal representative of the sensed process variable;
an analog-to-digital (A/D) converter receiving the sensor signal provided by the process variable sensor that senses the process variable and converts the sensor signal to a digital signal at a conversion rate;
a processor that receives the digital signal and provides a measurement output indicative of the process variable based upon the digital signal; and
a noise detector that receives the sensor signal at a refresh rate that is greater than the conversion rate, and generates a first value indicative of a number of positive noise events relative to a positive threshold value, and a second value indicative of a number of negative noise events relative to a negative threshold value, the processor evaluating the positive noise events and the negative noise events and generating a noise output that is indicative of detected noise based on the first and second values,wherein the noise detector comprises;
a positive noise threshold generator that receives the sensor signal and generates the positive threshold value as a positive voltage threshold; and
a negative noise threshold generator that receives the sensor signal and generates the negative threshold value as a negative voltage threshold.
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Abstract
A process variable transmitter, includes an analog-to-digital (A/D) converter that receives a sensor signal provided by a sensor that senses a process variable and converts the sensor signal to a digital signal. A processor receives the digital signal and provides a measurement output indicative of the digital signal. A noise detector receives the sensor signal and generates a first value indicative of a number of positive noise events relative to a positive threshold value and a second value indicative of a number of negative noise events relative to a negative threshold value. The processor evaluates the noise count and generates a noise output, indicative of detected noise, based on the first and second values.
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Citations
21 Claims
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1. A process variable transmitter, comprising:
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a process variable sensor configured to sense a process variable of an industrial process and responsively provide a sensor signal representative of the sensed process variable; an analog-to-digital (A/D) converter receiving the sensor signal provided by the process variable sensor that senses the process variable and converts the sensor signal to a digital signal at a conversion rate; a processor that receives the digital signal and provides a measurement output indicative of the process variable based upon the digital signal; and a noise detector that receives the sensor signal at a refresh rate that is greater than the conversion rate, and generates a first value indicative of a number of positive noise events relative to a positive threshold value, and a second value indicative of a number of negative noise events relative to a negative threshold value, the processor evaluating the positive noise events and the negative noise events and generating a noise output that is indicative of detected noise based on the first and second values, wherein the noise detector comprises; a positive noise threshold generator that receives the sensor signal and generates the positive threshold value as a positive voltage threshold; and a negative noise threshold generator that receives the sensor signal and generates the negative threshold value as a negative voltage threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of sensing a process variable in a process variable transmitter, comprising:
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sensing the process variable with a process variable sensor and responsively providing an analog sensor signal; receiving the analog sensor signal from the sensor indicative of the process variable; converting the analog sensor signal to a digital signal with an analog to digital converter at a conversion rate; during conversion of the analog sensor signal to the digital signal, accumulating positive noise counts in a positive noise accumulator with a noise count accumulator that are indicative of noise events that exceed a positive noise threshold, and negative noise counts in a negative noise accumulator that are indicative of noise events that exceed a negative noise threshold, at a refresh rate that is greater than the conversion rate; characterizing noise on the analog sensor signal based on the positive noise counts and the negative noise counts with a processor; and generating an output on a process control loop indicative of the digital signal and the characterization of the noise on the analog sensor signal. - View Dependent Claims (19, 20)
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21. A process variable transmitter, comprising:
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a process temperature sensor configured to sense a process temperature of an industrial process, and responsively provide a process temperature sensor signal; an analog-to-digital (A/D) converter receiving the process temperature sensor signal provided by the process temperature sensor that senses a process temperature and converts the temperature sensor signal to a digital signal at a conversion rate; a processor that receives the digital signal and controls current on a process control loop to provide a measurement output indicative of the digital signal; and a noise detector that receives the process temperature sensor signal and generates, during conversion of the process temperature sensor signal to the digital signal at a refresh rate that is greater than the conversion rate, a first count value indicative of a number of positive noise events relative to a positive threshold value and a second count value indicative of a number of negative noise events relative to a negative threshold value, the processor generating a noise output that is indicative of a characteristic of detected noise based on the first and second count values, wherein the noise detector comprises; a positive noise threshold generator that receives the process temperature sensor signal and generates the positive threshold value as a positive voltage threshold; and a negative noise threshold generator that receives the process temperature sensor signal and generates the negative threshold value as a negative voltage threshold.
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Specification