Device in a process system for determining statistical parameter
First Claim
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1. A process field device coupled to a process control loop, comprising:
- a process variable input to provide a process variable related to a process;
computing circuitry configured to calculate a statistical parameter of the process variable; and
output circuitry configured to output the statistical parameter on the process control loop for use in a statistical process control system.
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Abstract
A process device couples to a process control loop. The process device receives process signals. A memory in the process device contains a nominal parameter value and a rule. Computing circuitry calculates a statistical parameter of the process signal and operates on the statistical parameter and the stored nominal value based upon the stored rule and responsively provides an event output based upon the operation. Output circuitry provides an output in response to the event output. The statistical parameter can be used in statistical process control systems.
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16 Claims
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1. A process field device coupled to a process control loop, comprising:
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a process variable input to provide a process variable related to a process;
computing circuitry configured to calculate a statistical parameter of the process variable; and
output circuitry configured to output the statistical parameter on the process control loop for use in a statistical process control system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
a sensor providing a sensor output related to the process; and
an analog to digital converter which converts the sensor output into a digitized process variable.
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7. The apparatus of claim 6 wherein the sensor is selected from the group consisting of pressure, temperature, pH, flow, turbidity, level, position, conductivity, motor current, motor back emf and vibration sensors.
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8. The apparatus of claim 1 including an inference engine configured to perform diagnostics on the process control loop.
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9. The apparatus of claim 1 wherein the computing circuitry monitors the statistical parameter during normal operation of the process control loop and thereby generates the trained value.
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10. The apparatus of claim 1 wherein the process field device comprises a transmitter.
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11. A method performed in a process field device for a statistical process control system, comprising:
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obtaining a process variable related to a process;
calculating a statistical parameter of the process variable;
outputting the statistical parameter on a process control loop for use in statistical process control. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification