US 6,519,546 B1Grant

Auto correcting temperature transmitter with resistance based sensor

Issue Date:2003-02-11

•36 Claims

•4 Drawing Sheets

Abstract

A transmitter in a process control system includes a resistance-based sensor sensing a process variable and providing a sensor output. Self heating circuitry coupled to the sensor provides a self heating signal related to the sensor. Analog-to-digital conversion circuitry coupled to the sensor output provides a digitized sensor output, and transmitter output diagnostic correction circuitry provides an auto corrected output as a function of the self heating signal output or in another embodiment, the transmitter outputs a residual life estimate of the sensor as a function of the self heating index. A novel method of calculating the self heating index is also disclosed, which is applicable to various methods for providing a diagnostic transmitter output.

Metadata

Assignee

Rosemount Inc.

Inventors

Evren Eryurek
Jogesh Warrior

Application Information

Application Number:US 09/175,832

Filing Date:1998-10-19

Priority Date:1996-11-07

Art Unit:7

Classifications

IPC:

G06F 1900

Field of Search:

374 1374172702 99702130702133702136

Patent Drawings (4 sheets)

Description

[0002] This is a Continuation-In-Part application of application Ser. No. 09/016,216, filed Jan. 30, 1998 abandoned which is a Continuation-In-Part of application U.S Ser. No. 08/744,980, filed on Nov. 7, 1996 now U.S. Pat. No. 5,828,567.

Background of the Invention

[0003] The present invention relates to transmitters of the type used in the process control industry. More specifically, the invention relates to diagnostics for process control transmitters which include a resistance based temperature sensor.

[0004] Process control transmitters are used to monitor process variables in industrial processes. For example, a transmitter might monitor temperature and transmit such information back to a control room. Furthermore, some transmitters are capable of performing the control function directly. In order to monitor a process variable, the transmitter must include a sensor, for example, an RTD which is a resistance based temperature sensor.

[0005] As the RTD sensor ages or is subjected to harsh environmental conditions, the accuracy of the sensor tends to degrade. It is possible to compensate for this degradation by periodically recalibrating the transmitter. Typically, this requires an operator to enter the field and perform a calibration process on-site on the transmitter. This is both inconvenient and time consuming for the operator. Further, it is difficult to determine the condition of a sensor, prior to its ultimate failure.

[0006] It is also necessary for the sensors to be periodically replaced as they age. However, it is difficult to determine precisely when a replacement is necessary. Therefore, sensors are typically replaced well before their failure or, in some cases, they may fail unexpectedly.

Summary of the Invention

[0007] A transmitter in a process control system includes a resistance-based sensor sensing a process variable and providing a sensor output. Self heating circuitry coupled to the sensor provides a self heating signal related to the sensor. Analog-to-digital conversion circuitry coupled to the sensor output provides a digitized sensor output, and transmitter output diagnostic correction circuitry provides an auto corrected output as a function of the self heating signal output or in another embodiment, the transmitter outputs a residual life estimate of the sensor as a function of the self heating index. A novel method of calculating the self heating index is also disclosed, for use in the present invention.

Brief Description of the Drawings

[0008] FIG. 1 shows a process control system including a transmitter in accordance with the present invention.

[0009] FIG. 2 is a block diagram of a transmitter of the present invention.

[0010] FIG. 3 is a simplified block diagram of a transmitter in accordance with one embodiment of the invention.

[0011] FIG. 4 is a simplified block diagram in accordance with an embodiment of the present invention.

Detailed Description of the Preferred Embodiments

[0012] FIG. 1 is a diagram of process control system 2 including field mounted temperature transmitter 40 and a valve controller 12 coupled electrically to control room 4 over a two wire process control loops 6 and 14, respectively. Transmitter 40, mounted on a manifold and connected to the pipe via a manifold, monitors the temperature of process fluid in process piping 18. However, the present invention applies to any resistance based process variable measurement such as a resistance based pressure measurement or a resistance based pH measurement. Transmitter 40 transmits temperature information to control room 4 over loop 6 by controlling the current flowing through loop 6. For example, the current flowing through loop 6 may be controlled between 4 and 20 mA and properly calibrated to indicate temperature. Additionally or in the alternative, transmitter 40 may transmit digital information related to temperature over loop 6 to control room 4 such as in a HART® or an all digital protocol such as Fieldbus. Transmitter 40 includes circuitry described herein in more detail which provides advanced diagnostics related to temperature sensor operation.

[0013] One aspect of the present invention includes a recognition of a close correlation, in some cases linear relationship, of the SH index to the “alpha” and/or R₀of the sensor. As is known, alpha and/or R₀of a sensor is related to sensor calibration and therefore to sensor lifetime. Accordingly, if the SH index is measured, the lifetime of the sensor can be estimated. Furthermore, the sensor output can be corrected in real-time as a function of the amount of degradation (e.g., the difference between a preselected value of the SH index and the true current value of the SH index) . This provides an autocorrection to the transmitter output.

[0014] One aspect of the invention includes a new technique for determining the self heating (SH) index of an RTD sensor. Typically, prior art self heating index measurement was performed by monitoring temperature change in the RTD due to an applied current. However, in a transmitter it is impractical to perform such a measurement due to power limitations and the necessity of a separate temperature measurement. The present invention includes defining the self heating index as the change in sensor resistance for a given change in the power input to the RTD sensor. This technique is preferable for a temperature transmitter because it does not require the RTD to be calibrated. Furthermore, the technique does not require the RTD to be removed from the process such that real-time data can be collected without the trouble and cost of interrupting the process. The self heating index can be calculated in a transmitter by applying two different input currents, for example, 5 mA and 15 mA. The resulting voltages across the RTD are measured and the resistance of the sensor is calculated at the two different currents using the equation R =V/I. The power applied to the RTD is determined at the two different currents as P =I·V. The self heating index is calculated in accordance with equation 1:

\begin{matrix} SHI = \frac{R_{1} - R_{2}}{P_{1} - P_{2}} & Eq . 1 \end{matrix}

[0015] The invention can be practiced in any of a number of places in a process system control system. In particular, the present invention as realized in software and a microprocessor, can reside in a central controller or even a final control element 12 such as a valve, motor or switch as shown in FIG. 1. Furthermore, modern digital protocols such as Fieldbus, Profibus and others allow for the software which practices the present invention to be communicated between elements in a process control system, and also provide for process variables to be sensed in one transmitter and then sent to the software.

[0016] FIG. 2 is a simplified block diagram of a temperature transmitter 40 connected to RTD temperature sensor 10 in accordance with the present invention. Transmitter 40 includes terminal block 44, current source 45, multiplexer 46, differential amplifier 48, high accuracy A/D converter 50, microprocessor 52, clock circuit 54, memory 56 and input-output circuit 58.

[0017] Terminal block 44 includes terminals 1 through 5 for coupling to, for example, RTD temperature sensor 10. Sensor 10 can be either internal or external to transmitter 40. Sensor 10 includes RTD sensor element 61 having a resistance R₁which varies with changes in the ambient temperature. Leads 16 include four element leads 62, 64, 66 and 68. Lead 62 is connected between sensor element 61 and terminal 4, lead 64 is connected between sensor element 61 and terminal 3, lead 66 is connected between sensor element 61 and terminal 2, and lead 68 is connected between sensor element 61 and terminal 1.

[0018] Current source 45 is connected to terminal block 44 and supplies a measurement current I_sthrough terminal 4, sensor element 61, terminal 1, reference resistance R_REF, pull-down resistance R₂and ground terminal 72. Sensor element 61 develops a voltage drop across terminals 2 and 3 which is a function of the resistance R₁and thus the temperature of sensor element 61. Reference resistor R_REFis connected between terminal 1 and pull-down resistor R₂.

[0019] Multiplexer 46 is divided into two sections, an active multiplexer having an output connected to the non-inverting input of differential amplifier 48 and a reference multiplexer having an output connected to the inverting input of differential amplifier 48. Microprocessor 52 controls multiplexer 46 to multiplex appropriate sets of analog signals, including signals from terminals 1 through 3, to the non-inverting and inverting inputs of differential amplifier 48. Differential amplifier 48 has an output connected to A/D converter 50. In one embodiment, A/D converter 50 has an accuracy of 17 bits and a conversion rate of 14 samples/second. A/D converter 50 converts the voltage at the output of differential amplifier 48 into a digital value and provides that value to microprocessor 52 for analysis or for communication over process control loop 6 through input-output circuit 58.

[0020] Input-output circuit 58, in a preferred embodiment, includes a HART® communication section, a FIELDBUS communication section and a 4-20 mA analog loop section for analog or bi-directional digital communicating over loop 6 according to a selected protocol in a known manner. Other protocols can also be used, for example, a four-wire configuration may be employed in which power is received from a separate source. Loop 6 also provides power to the various components of transmitter 40 through input-output circuit 58. Preferably, transmitter 40 is wholly (completely) powered by the two-wire loop 6.

[0021] Memory 56 stores instructions and information for microprocessor 52, which operates at a speed determined by clock circuit 60. Clock circuit 60 includes a real time clock and a precision high speed clock, which are also used to sequence the operation of A/D converter 50. Microprocessor 52 performs several functions, including control of multiplexer 46 and A/D converter 50, control of communications over loop 6, temperature compensation, storage of transmitter configuration parameters and performing sensor diagnostics.

[0022] Microprocessor 52 employs the following equation to compute the temperature of RTD sensor element 61:

\begin{matrix} R_{1} = \frac{V_{R1}}{V_{RREF}} (R_{REFNOM}) & Equation 2 \end{matrix}


	R	= resistance of RTD sensor element 61;
	V	= voltage drop across the RTD sensor element 61;
	V	= voltage drop across resistance R
	R	= nominal resistance of the reference resistance
		R

[0023] Microprocessor 52 measures the voltage drop V_R1across RTD sensor element 61 between terminals 2 and 3, and the voltage drop (V_RREF) across reference resistance R_REFwith multiplexer 46. In a four-wire resistance measurement such as the one shown in FIG. 2, the voltage drop across the connections to terminals 2 and 3 is largely eliminated, since substantially all of the current I_sflows between terminals 1 and 4, and has little impact on the accuracy of the measurement. Microprocessor 52 converts the measured resistance R₁into temperature units with a look-up table or suitable equations stored in memory 30. For example, one such equation is the Callender-Van Dusen equation which is:

\begin{matrix} R (t) = R_{0} {1 + α (t - δ (\frac{t}{100}) (\frac{t}{100} - 1) - β (\frac{t}{100} - 1) {(\frac{t}{100})}^{3})} & Eq . 3 \end{matrix}

[0024] Where:

[0025] R(t)=Resistance at temperature t, in Ohms.

[0026] R₀=Resistance at temperature 0, in Ohms.

[0027] t=Temperature, deg C.

[0028] α, δ, β=Calibration constants.

[0029] β=0 for t>0 deg C.

[0030] However, both stored lookup tables or the equation 2 must be properly calibrated for a particular RTD temperature sensor. Further, such calibration tends to change over time as the alpha (α) for the sensor drifts. Calibrating an RTD requires an accurate thermometer reference to obtain a number of correct temperature values in order to accurately determine the constants α and δ. Equation 3 and transmitter calibration are discussed in PRT Handbook Bulletin 1042, dated February 1985, published by Rosemount and incorporated by reference into this application.

[0031] The SH index is calculated when microprocessor 52 actuates switch 138 to couple current source 140 to sensor 61. Pand R₁of equation 1 are calculated with current I_SHfrom source 140 flowing through sensor 61. Microprocessor 52 determines P₂and R₂due to current I_sfrom source 45. The SH index is calculated using equation 1. If transmitter 40 is completely powered from loop 6, the currents I_SHand I_sare limited to the current I in loop 6, less any current required to operate circuitry in transmitter 40.

[0032] Microprocessor 52 performs diagnostics related to operation of transmitter 40 using the SH index. The following describes a number of embodiments for realizing the diagnostic circuitry in transmitter 40. Such diagnostics include determining sensor health, performing a residual lifetime estimate may be representative of an impending sensor failure, or performing an autocorrection to the temperature measurement.

[0033] Another aspect of the present invention includes the use of the self heating index to correct the temperature measurement to reduce errors due to drift in alpha (α) and/or R₀. As the RTD sensor ages, the constant(s) alpha (α) and/or R₀(given in equation 3) for the sensor, changes thereby causing inaccuracies in the temperature measurements. It has been discovered that there is a substantially linear relationship between the SH index and error in the temperature measurement caused by drift in alpha (α) and/or R₀. The temperature can be corrected using the equation:

[0034] T_corrected=T_measuredK(ΔSHI) Eq. 4

[0035] where:

[0036] T_measuredis the measured temperature;

[0037] K is a constant of proportionality which is a function of the change in the self heating index; and

[0038] T_correctedis the autocorrected temperature.

[0039] The relationship between K and the change in SHI may be determined experimentally. Determination of K may be through an equation or, in one preferred embodiment, with a lookup table stored in memory 56 as a function of change in SHI. Similarly, SHI, or change in SHI, can be correlated to alpha (α) and R₀, or changes in these constants. Further, it is within the scope of the present invention to correlate SHI or ΔSHI to other constraints in Equation 3.

[0040] FIG. 3 is a block diagram 150 illustrating the present invention as it relates to autocorrection of the temperature output as a function of the SH index. Diagram 150 shows operations which would typically be performed by microprocessor 52 in FIG. 2. At block 152, the previous value of the self heating index (SHI₁) is obtained, for example, from memory 56. This value may have been stored in memory during manufacture, previously generated by microprocessor 52 or determined and stored when the transmitter was commissioned or even at a preselected time during operation of transmitter 40. At block 154 the current value of the SH index (SHI₂) is determined by microprocessor 52. If the rate of change, m is greater than or equal to a maximum allowable rate of change (m_MAX), decision block 158 provides an alarm output. In general, a value representative of the difference between SHI₂and SHI₁is assessed at block 156. A preferred method for this differencing function is to calculate the slope over time of the two SHI values. However, other methods of assessing the amount of difference, some as simple as comparing SH₂to a threshold value, can be implemented without block 156. The output may be transmitted, for example, over loop 6 to indicate that the sensor has degradated to such an extent that failure is imminent and replacement is necessary. Other types of diagnostics may also be performed such as those set forth in the parent application U.S. Ser. No. 08/744,980, filed Nov. 7, 1996. The value of m_MAXis stored in memory 56 and may be user configurable based upon the accuracy desired for a particular process. The alarming function at block 158 is optional, but preferred to the present invention.

[0041] If the alarm condition does not exist, control passes to decision block 160 in which the measured self heating index (SHI₂) is compared with the stored self heating index (SHI₁). If they are approximately the same, control is passed to block 162 and the temperature is determined. If, on the other hand, there is a difference between the two values, a new value for the ΔSHI in equation 4 is calculated by microprocessor 52 at block 164. Further, other more complex curve fitting techniques can be used to correlate SHI with sensor calibration. Control is passed to block 162 and the new value for ΔSHI in equation 4 is used in determining temperature. The new value for ΔSHI is stored in memory to replace the previous value.

[0042] The various functions set forth in FIG. 3 may be performed remotely, in a process control device, in the control room, in a computer located off-site or in a combination of these locations. Generally, the invention can be practiced in any of a number of places in a process system control system. In particular, the present invention as realized in software and a microprocessor, can reside in a central controller or even a final control element such as a valve, motor or switch as shown in FIG. 1. Furthermore, modern digital protocols such as Fieldbus, Profibus and others allow for the software which practices the present invention to be communicated between elements in a process control system, and also provide for process variables to be sensed in one transmitter and then sent to the software.

[0043] One embodiment of diagnostic circuitry in the present invention uses empirical models or polynomial curve-fitting which are functions of SH index. For example, a polynomial which is a function of the SH index is used for computing the residual lifetime estimate. The constants and/or the equations may be sent over the two wire loop to transmitter 40. Another diagnostic circuit is implemented with a multi-layer neural network. Although a number of training algorithms can be used to develop a neural network model for different goals, one embodiment includes the known Backpropagation Network (BPN) to develop neural network modules which will capture the nonlinear relationship among a set of input and outputs(s).

[0044] Another embodiment of diagnostic circuitry 52 uses a set of if—then rules to reach a conclusion on the status of the temperature sensor RTD 61. The SH index is monitored and its present value is compared to upper and lower boundaries. The upper and lower boundaries are empirically set by testing of many RTD sensors. A decision is made based upon the comparison.

[0045] In another aspect of the invention, the rate of change (ROC) of the SH index is correlated with life expectancy of sensor 61. The ROC of the SH index is provided to the diagnostic circuitry implemented in microprocessor 52 which provides an output indicative of expected life, including a warning when the expected remaining sensor life has dropped below a minimum value.

[0046] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

Certificate of Correction present

The claims shown below may not include correction changes. Use the corrected PDF for authoritative text.

What is claimed is:

1. A transmitter in a process control system, comprising:

a resistance temperature sensor sensing a process variable and providing a sensor output;

self heating circuitry coupled to the sensor providing a self heating signal related to a self heating index of the sensor;

analog to digital conversion circuitry coupled to the sensor output and the sensor monitoring circuitry and providing a digitized sensor output and a digitized self heating signal;

output circuitry coupled to a process control loop for transmitting a signal related to sensor temperature; and

diagnostic circuitry coupled to the digitized self heating signal responsively providing a diagnostic output related to sensor calibration as a function of the digitized self heating signal.

2. The transmitter of claim 1 including a memory storing a set of expected results related to the self heating signal.

3. The transmitter of claim 1 wherein the diagnostic circuitry comprises a neural network.

4. The transmitter of claim 1 wherein the diagnostic circuitry comprises fuzzy logic.

5. The transmitter of claim 1 wherein the diagnostic circuitry provides a residual lifetime estimate output.

6. The transmitter of claim 5 wherein the diagnostic circuitry determines the residual lifetime estimate as a function of rate of change (ROC) of the digitized self heating signal.

7. The transmitter of claim 1 wherein the self heating circuitry includes a current source and voltage measurement circuitry.

8. The transmitter of claim 1 wherein the self heating circuitry determines the SH index as a function of a change in sensor resistance in response to a change in power applied to the sensor.

9. The transmitter of claim 8 wherein the SH index is calculated as (R₁-R₂)/(P₁-P₂).

10. The transmitter of claim 1 wherein the output circuitry calibrates the sensor temperature signal in response to the diagnostic output.

11. The transmitter of claim 1 wherein the calibration is a function of the self heating signal.

12. The transmitter of claim 1 wherein the diagnostic output is indicative of sensor life expectancy.

13. A method for diagnosing a resistance based temperature sensor in a process control transmitter, comprising:

sensing and digitizing resistance of the sensor to provide a digitized sensor output;

obtaining a self heating index (SHI) for the sensor;

providing a diagnostic output as a function of the SHI.

14. The method of claim 13 wherein obtaining the SHI comprises measuring change in sensor resistance in response to a change in power applied to the sensor.

15. The method of claim 14 wherein the self heating index is calculated as (R₁-R₂)/(P₁-P₂).

16. The method of claim 13 including estimating residual life of the sensor based upon a rate of change of the SHI.

17. The method of claim 13 wherein obtaining the SHI includes sequentially injecting at least two different current levels into the sensor and measuring the resultant voltage drop across the sensor.

18. The method of claim 13 including determining sensor life expectancy as a function of the diagnostic output.

19. The method of claim 13 including determining temperature of the sensor as a function of the sensor output and the SHI.

20. A temperature transmitter for use in a process control system, comprising:

I/O circuitry adapted to coupled to a process control loop;

a resistance based temperature sensor;

a current source coupled to the sensor to inject a current into the sensor;

voltage measurement circuitry coupled to the sensor providing an output related to voltage drop across the sensor; and

diagnostic circuitry providing a self heating (SH) index output as a function of injected current and the voltage drop across the sensor.

21. The transmitter of claim 20 wherein the diagnostic circuitry provides a life expectancy output as a function of the SH index.

22. The transmitter of claim 20 including temperature measurement circuitry providing an output related to sensor temperature as a function of sensor resistance and the SH index.

23. The transmitter of claim 20 wherein the SH index is determined as a function of a change in sensor resistance in response to a change in power applied to the sensor.

24. The transmitter of claim 21 wherein the SH index is calculated as (R₁-R₂)/(P₁-P₂).

25. A temperature transmitter for use in a process control system, comprising:

a resistance temperature sensor sensing a process variable and providing a sensor output;

self heating circuitry coupled to the sensor providing a self heating signal related to a self heating index of the sensor;

analog to digital conversion circuitry coupled to the sensor output and the sensor monitoring circuitry and providing a digitized sensor output and a digitized self heating signal;

measurement circuitry calculating a measurement temperature of the temperature sensor as a function of the digitized sensor output and the digitized self heating signal; and

output circuitry coupled to the process control loop for transmitting the measured temperature on the loop.

26. The temperature transmitter of claim 25 wherein a constant R₀of the temperature sensor changes as a function of change in the self heating signal.

27. The temperature transmitter of claim 25 wherein a constant alpha (α) of the temperature sensor changes as a function of change in the self heating signal.

28. The temperature transmitter of claim 25 wherein the measured temperature is a function of the sensor signal times a constant K.

29. The temperature transmitter of claim 28 wherein the measured temperature is linearly related to K, where K is a function of the self heating index.

30. The temperature transmitter of claim 28 including a lookup table stored in a memory, the lookup table providing K as a function of the self heating signal.

31. The temperature transmitter of claim 25 including diagnostic circuitry coupled to the digitized self heating signal responsively providing a diagnostic output related to sensor calibration as a function of the digitized self heating signal.

32. The temperature transmitter of claim 25 including:

a current source coupled to the sensor to inject a current into the sensor;

voltage measurement circuitry coupled to the sensor providing an output related to voltage drop across the sensor; and

diagnostic circuitry providing a self heating (SH) index output as a function of injected current and the voltage drop across the sensor.

33. A transmitter in a process control system, comprising:

a resistance temperature sensor sensing a process variable and providing a sensor output;

self heating circuitry coupled to the sensor providing a self heating signal related to a self heating index of the sensor, the self heating index defined as a change in sensor resistance for a given change in power input to the sensor;

analog to digital conversion circuitry coupled to the sensor output and the sensor monitoring circuitry and providing a digitized sensor output and a digitized self heating signal;

output circuitry coupled to a process control loop for transmitting a signal related to sensor temperature; and

diagnostic circuitry coupled to the digitized self heating signal responsively providing a diagnostic output related to sensor calibration as a function of the digitized self heating signal.

34. A method for diagnosing a resistance based temperature sensor in a process control transmitter, comprising:

sensing and digitizing resistance of the sensor to provide a digitized resistance sensor output;

obtaining a self heating index (SHI) for the sensor, the self heating index defined as a change in sensor resistance for a given change in power input to the sensor;

providing a diagnostic output as a function of the SHI.

35. A temperature transmitter for use in a process control system, comprising:

I/O circuitry adapted to coupled to a process control loop;

a resistance based temperature sensor;

a current source coupled to the sensor to inject a current into the sensor;

voltage measurement circuitry coupled to the sensor providing an output related to voltage drop across the sensor; and

diagnostic circuitry providing a self heating (SH) index output as a function of injected current and the voltage drop across the sensor, the self heating index defined as a change in sensor resistance for a given change in power input to the sensor.

36. A temperature transmitter for use in a process control system; comprising:

a resistance temperature sensor sensing a process variable and providing a sensor output;

analog to digital conversion circuitry coupled to the sensor output and the sensor monitoring circuitry and providing a digitized sensor output and a digitized self heating signal;

measurement circuitry calculating a measurement temperature of the temperature sensor as a function of the digitized sensor output and the digitized self heating signal; and

output circuitry coupled to the process control loop for transmitting the measured temperature on the loop.

Patent Citations (262)

Patent	Date	Inventor	Cited By
US3096434(A)	1963-07-01	King	Applicant
US3404264(A)	1968-10-01	Kugler	Applicant
US3468164(A)	1969-09-01	Sutherland	Applicant
US3590370(A)	1971-06-01	Fleischer	Applicant
US3618592(A)	1971-11-01	Stewart et al.	Applicant
US3688190(A)	1972-08-01	Blum	Applicant
US3691842(A)	1972-09-01	Akeley	Applicant
US3701280(A)	1972-10-01	Stroman	Applicant
US3855858(A)	1974-12-01	Cushing	Applicant
US3973184(A)	1976-08-01	Raber	Applicant
USRE29383(E)	1977-09-01	Gallatin et al.	Applicant
US4058975(A)	1977-11-01	Gilbert et al.	Applicant
US4099413(A)	1978-07-01	Ohte et al.	Applicant
US4102199(A)	1978-07-01	Tsipouras	Applicant
US4122719(A)	1978-10-01	Carlson et al.	Applicant
US4249164(A)	1981-02-01	Tivy	Applicant
US4250490(A)	1981-02-01	Dahlke	Applicant
US4337516(A)	1982-06-01	Murphy et al.	Applicant
US4399824(A)	1983-08-01	Davidson	Applicant
US4517468(A)	1985-05-01	Kemper et al.	Applicant
US4530234(A)	1985-07-01	Cullick et al.	Applicant
US4635214(A)	1987-01-01	Kasai et al.	Applicant
US4642782(A)	1987-02-01	Kemper et al.	Applicant
US4644479(A)	1987-02-01	Kemper et al.	Applicant
US4649515(A)	1987-03-01	Thompson et al.	Applicant
US4668473(A)	1987-05-01	Agarwal	Applicant
US4707796(A)	1987-11-01	Calabro et al.	Applicant
US4720806(A)	1988-01-01	Schippers et al.	Applicant
US4736367(A)	1988-04-01	Wroblewski et al.	Applicant
US4736763(A)	1988-04-01	Britton et al.	Applicant
US4777585(A)	1988-10-01	Kokawa et al.	Applicant
US4831564(A)	1989-05-01	Suga	Applicant
US4841286(A)	1989-06-01	Kummer	Applicant
US4873655(A)	1989-10-01	Kondraske	Applicant
US4907167(A)	1990-03-01	Skeirik	Applicant
US4924418(A)	1990-05-01	Backman et al.	Applicant
US4934196(A)	1990-06-01	Romano	Applicant
US4939753(A)	1990-07-01	Olson	Applicant
US4964125(A)	1990-10-01	Kim	Applicant
US4988990(A)	1991-01-01	Warrior	Applicant
US4992965(A)	1991-02-01	Holter et al.	Applicant
US5005142(A)	1991-04-01	Lipchak et al.	Applicant
US5043862(A)	1991-08-01	Takahashi et al.	Applicant
US5053815(A)	1991-10-01	Wendell	Applicant
US5067099(A)	1991-11-01	McCown et al.	Applicant
US5081598(A)	1992-01-01	Bellows et al.	Applicant
US5089979(A)	1992-02-01	McEachern et al.	Applicant
US5089984(A)	1992-02-01	Struger et al.	Applicant
US5098197(A)	1992-03-01	Shepard et al.	Applicant
US5099436(A)	1992-03-01	McCown et al.	Applicant
US5103409(A)	1992-04-01	Shimizu et al.	Applicant
US5111531(A)	1992-05-01	Grayson et al.	Applicant
US5121467(A)	1992-06-01	Skeirik	Applicant
US5122794(A)	1992-06-01	Warrior	Applicant
US5122976(A)	1992-06-01	Bellows et al.	Applicant
US5130936(A)	1992-07-01	Sheppard et al.	Applicant
US5134574(A)	1992-07-01	Beaverstock et al.	Applicant
US5137370(A)	1992-08-01	McCulloch et al.	Applicant
US5142612(A)	1992-08-01	Skeirik	Applicant
US5143452(A)	1992-09-01	Maxedon et al.	Applicant
US5148378(A)	1992-09-01	Shibayama et al.	Applicant
US5167009(A)	1992-11-01	Skeirik	Applicant
US5175678(A)	1992-12-01	Frerichs et al.	Applicant
US5193143(A)	1993-03-01	Kaemmerer et al.	Applicant
US5197114(A)	1993-03-01	Skeirik	Applicant
US5197328(A)	1993-03-01	Fitzgerald	Applicant
US5212765(A)	1993-05-01	Skeirik	Applicant
US5214582(A)	1993-05-01	Gray	Applicant
US5224203(A)	1993-06-01	Skeirik	Applicant
US5228780(A)	1993-07-01	Shepard et al.	Applicant
US5235527(A)	1993-08-01	Ogawa et al.	Applicant
US5265031(A)	1993-11-01	Malczewski	Applicant
US5265222(A)	1993-11-01	Nishiya et al.	Applicant
US5269311(A)	1993-12-01	Kirchner et al.	Applicant
US5274572(A)	1993-12-01	O'Neill et al.	Applicant
US5282131(A)	1994-01-01	Rudd et al.	Applicant
US5282261(A)	1994-01-01	Skeirik	Applicant
US5293585(A)	1994-03-01	Morita	Applicant
US5303181(A)	1994-04-01	Stockton	Applicant
US5305230(A)	1994-04-01	Matsumoto et al.	Applicant
US5311421(A)	1994-05-01	Nomura et al.	Applicant
US5317520(A)	1994-05-01	Castle	Applicant
US5327357(A)	1994-07-01	Feinstein et al.	Applicant
US5333240(A)	1994-07-01	Matsumoto et al.	Applicant
US5347813(A)	1994-09-01	Orr et al.	Applicant
US5349541(A)	1994-09-01	Alexandro, Jr. et al.	Applicant
US5357449(A)	1994-10-01	Oh	Applicant
US5361628(A)	1994-11-01	Marko et al.	Applicant
US5365423(A)	1994-11-01	Chand	Applicant
US5365787(A)	1994-11-01	Hernandez et al.	Applicant
US5367612(A)	1994-11-01	Bozich et al.	Applicant
US5384699(A)	1995-01-01	Levy et al.	Applicant
US5386373(A)	1995-01-01	Keeler et al.	Applicant
US5388465(A)	1995-02-01	Okaniwa et al.	Applicant
US5394341(A)	1995-02-01	Kepner	Applicant
US5394543(A)	1995-02-01	Hill et al.	Applicant
US5404064(A)	1995-04-01	Mermelstein et al.	Applicant
US5408406(A)	1995-04-01	Mathur et al.	Applicant
US5408586(A)	1995-04-01	Skeirik	Applicant
US5414645(A)	1995-05-01	Hirano	Applicant
US5419197(A)	1995-05-01	Ogi et al.	Applicant
US5430642(A)	1995-07-01	Nakajima et al.	Applicant
US5436705(A)	1995-07-01	Raj	Applicant
US5440478(A)	1995-08-01	Fisher et al.	Applicant
US5442639(A)	1995-08-01	Crowder et al.	Applicant
US5467355(A)	1995-11-01	Umeda et al.	Applicant
US5469070(A)	1995-11-01	Koluvek	Applicant
US5469156(A)	1995-11-01	Kogure	Applicant
US5469735(A)	1995-11-01	Watanabe	Applicant
US5469749(A)	1995-11-01	Shimada et al.	Applicant
US5481199(A)	1996-01-01	Anderson et al.	Applicant
US5483387(A)	1996-01-01	Bauhahn et al.	Applicant
US5485753(A)	1996-01-01	Burns et al.	Applicant
US5486996(A)	1996-01-01	Samad et al.	Applicant
US5488697(A)	1996-01-01	Kaemmerer et al.	Applicant
US5489831(A)	1996-02-01	Harris	Applicant
US5495769(A)	1996-03-01	Broden et al.	Applicant
US5510799(A)	1996-04-01	Wishart	Applicant
US5511004(A)	1996-04-01	Dubost et al.	Applicant
US5526293(A)	1996-06-01	Mozumber et al.	Applicant
US5539638(A)	1996-07-01	Keeler et al.	Applicant
US5548528(A)	1996-08-01	Keeler et al.	Applicant
US5560246(A)	1996-10-01	Bottinger et al.	Applicant
US5561599(A)	1996-10-01	Lu	Applicant
US5570300(A)	1996-10-01	Henry et al.	Applicant
US5572420(A)	1996-11-01	Lu	Applicant
US5573032(A)	1996-11-01	Lenz et al.	Applicant
US5591922(A)	1997-01-01	Segeral et al.	Applicant
US5598521(A)	1997-01-01	Kilgore et al.	Applicant
US5600148(A)	1997-02-01	Cole et al.	Applicant
US5623605(A)	1997-04-01	Keshav et al.	Applicant
US5633809(A)	1997-05-01	Wissenbach et al.	Applicant
US5637802(A)	1997-06-01	Frick et al.	Applicant
US5640491(A)	1997-06-01	Bhat et al.	Applicant
US5661668(A)	1997-08-01	Yemini et al.	Applicant
US5665899(A)	1997-09-01	Willcox	Applicant
US5669713(A)	1997-09-01	Schwartz et al.	Examiner
US5671335(A)	1997-09-01	Davis et al.	Applicant
US5675504(A)	1997-10-01	Serodes et al.	Applicant
US5675724(A)	1997-10-01	Beal et al.	Applicant
US5680109(A)	1997-10-01	Lowe et al.	Applicant
US5700090(A)	1997-12-01	Eryurek	Examiner
US5703575(A)	1997-12-01	Kirkpatrick	Examiner
US5704011(A)	1997-12-01	Hansen et al.	Applicant
US5705978(A)	1998-01-01	Frick et al.	Applicant
US5708211(A)	1998-01-01	Jepson et al.	Applicant
US5708585(A)	1998-01-01	Kushion	Applicant
US5710370(A)	1998-01-01	Shanahan et al.	Applicant
US5713668(A)	1998-02-01	Lunghofer et al.	Applicant
US5719378(A)	1998-02-01	Jackson, Jr. et al.	Examiner
US5736649(A)	1998-04-01	Kawasaki et al.	Applicant
US5741074(A)	1998-04-01	Wang et al.	Examiner
US5742845(A)	1998-04-01	Wagner	Applicant
US5746511(A)	1998-05-01	Eryurek et al.	Examiner
US5747701(A)	1998-05-01	Marsh et al.	Applicant
US5752008(A)	1998-05-01	Bowling	Applicant
US5764891(A)	1998-06-01	Warrior	Applicant
US5781878(A)	1998-07-01	Mizoguchi et al.	Applicant
US5801689(A)	1998-09-01	Huntsman	Applicant
US5805442(A)	1998-09-01	Crater et al.	Applicant
US5817950(A)	1998-10-01	Wiklund et al.	Applicant
US5828567(A)	1998-10-01	Eryurek et al.	Examiner
US5829876(A)	1998-11-01	Schwartz et al.	Examiner
US5848383(A)	1998-12-01	Yunus	Examiner
US5859964(A)	1999-01-01	Wang et al.	Applicant
US5876122(A)	1999-03-01	Eryurek	Examiner
US5880376(A)	1999-03-01	Sai et al.	Applicant
US5887978(A)	1999-03-01	Lunghofer et al.	Applicant
US5908990(A)	1999-06-01	Cummings	Applicant
US5923557(A)	1999-07-01	Eidson	Applicant
US5924086(A)	1999-07-01	Mathur et al.	Applicant
US5926778(A)	1999-07-01	Poppel	Examiner
US5940290(A)	1999-08-01	Dixon	Applicant
US5956663(A)	1999-09-01	Eryurek	Examiner
US5970430(A)	1999-10-01	Burns et al.	Applicant
US6014902(A)	2000-01-01	Lewis et al.	Applicant
US6016523(A)	2000-01-01	Zimmerman et al.	Applicant
US6016706(A)	2000-01-01	Yamamoto et al.	Applicant
US6017143(A)	2000-01-01	Eryurek et al.	Applicant
US6038579(A)	2000-03-01	Sekine	Applicant
US6045260(A)	2000-04-01	Schwartz et al.	Examiner
US6047220(A)	2000-04-01	Eryurek	Applicant
US6047222(A)	2000-04-01	Burns et al.	Applicant
US6052655(A)	2000-04-01	Kobayashi et al.	Applicant
US6072150(A)	2000-06-01	Sheffer	Applicant
US6112131(A)	2000-08-01	Ghorashi et al.	Applicant
US6119047(A)	2000-09-01	Eryurek et al.	Applicant
US6119529(A)	2000-09-01	DiMarco et al.	Applicant
US6192281(B1)	2001-02-01	Brown et al.	Applicant
US6195591(B1)	2001-02-01	Nixon et al.	Applicant
US6199018(B1)	2001-03-01	Quist et al.	Applicant
US6236948(B1)	2001-05-01	Eck et al.	Applicant
US6263487(B1)	2001-07-01	Stripf et al.	Applicant
US6298377(B1)	2001-10-01	Hartikainen et al.	Applicant
US6311136(B1)	2001-10-01	Henry et al.	Applicant
US6327914(B1)	2001-12-01	Dutton	Applicant
DE3213866	1983-10-01		Applicant
DE3540204	1986-09-01		Applicant
DE4008560	1990-09-01		Applicant
DE4343747	1994-06-01		Applicant
DE4433593	1995-06-01		Applicant
DE19502499	1996-08-01		Applicant
DE29600609	1997-03-01		Applicant
DE19704694	1997-08-01		Applicant
DE19930660	1999-07-01		Applicant
DE29917651	2000-12-01		Applicant
EP122622	1984-10-01		Applicant
EP413814	1991-02-01		Applicant
EP487419	1992-05-01		Applicant
EP512794	1992-05-01		Applicant
EP594227	1994-04-01		Applicant
EP624847	1994-11-01		Applicant
EP644470	1995-03-01		Applicant
EP807804	1997-11-01		Applicant
EP825506	1998-02-01		Applicant
EP827096	1998-03-01		Applicant
EP838768	1998-04-01		Applicant
EP1058093	1999-05-01		Applicant
FR2302514	1976-09-01		Applicant
FR2334827	1977-07-01		Applicant
GB928704	1963-06-01		Applicant
GB1534280	1978-11-01		Applicant
GB2310346	1997-08-01		Applicant
JP58-129316	1983-08-01		Applicant
JP59-116811	1984-07-01		Applicant
JP59163520	1984-09-01		Applicant
JP59-211196	1984-11-01		Applicant
JP59-211896	1984-11-01		Applicant
JP60-507	1985-01-01		Applicant
JP60-76619	1985-05-01		Applicant
JP60-131495	1985-07-01		Applicant
JP60174915	1985-09-01		Applicant
JP62-30915	1987-02-01		Applicant
JP64-1914	1989-01-01		Applicant
JP64001914	1989-01-01		Applicant
JP64-72699	1989-03-01		Applicant
JP2-5105	1990-01-01		Applicant
JP3229124	1991-11-01		Applicant
JP5-122768	1993-05-01		Applicant
JP6242192	1994-09-01		Applicant
JP7-63586	1995-03-01		Applicant
JP7234988	1995-09-01		Applicant
JP8-54923	1996-02-01		Applicant
JP8-136386	1996-05-01		Applicant
JP8-166309	1996-06-01		Applicant
JP8247076	1996-09-01		Applicant
JP2712625	1997-10-01		Applicant
JP2712701	1997-10-01		Applicant
JP2753592	1998-03-01		Applicant
JP7225530	1998-05-01		Applicant
JP10-232170	1998-09-01		Applicant
JP11083575	1999-03-01		Applicant
WO94/25933	1994-11-01		Applicant
WO96/11389	1996-04-01		Applicant
WO96/12993	1996-05-01		Applicant
WO96/39617	1996-12-01		Applicant
WO97/21157	1997-06-01		Applicant
WO97/25603	1997-07-01		Applicant
WO98/06024	1998-02-01		Applicant
WO98/13677	1998-04-01		Applicant
WO98/20469	1998-05-01		Applicant
WO/70531	2000-11-01		Applicant

Non-Patent Literature (141)

Wang Lei et al., “Improving Dynamic Performance of Temperature Sensors with Fuzzy Control Technique”, IEEE, 1992.Applicant
“Development of a Long-Life, High-Reliability Remotely Operated Johnson Noise Thermometer,” by R.L. Shepard et al., ISA, 1991, pp. 77-84.Applicant
“Application of Johnson Noise Thermometry to Space Nuclear Reactors,” by M.J. Roberts et al., Presented at the 6th Symposium on Space Nuclear Power Systems, Jan. 9-12, 1989.Applicant
“Sensor and Device Diagnostics for Predictive and Proactive Maintenance”, by B. Boynton, A Paper Presented at the Electric Power Research Institute—Fossil Plant Maintence Conference in Baltimore, Maryland, Jul. 29-Aug. 1, 1996, pp. 50-1-50-6.Applicant
“Smart Field Devices Provide New Process Data, Increase System Flexibility,” by Mark Boland, I&CS, Nov. 1994, pp. 45-51.Applicant
“Wavelet Analysis of Vibration, Part I: Theory1,” by D.E. Newland, Journal of Vibration and Acoustics, vol. 116, Oct. 1994, pp. 409-416.Applicant
“Wavelet Analysis of Vibration, Part 2: Wavelet Maps,” by D.E. Newland, Journal of Vibration and Acoustics, vol. 116, Oct. 1994, pp. 417-425.Applicant
“Field-based Architecture is Based on Open Systems, Improves Plant Performance”, by P. Cleaveland, I&CS, Aug. 1996, pp. 73-74.Applicant
“Tuned-Circuit Dual-Mode Johnson Noise Thermometers,” by R.L. Shepard et al., Apr. 1992.Applicant
“Tuned Circuit Johnson Noise Thermometry,” by Michael Roberts et al., 7th Symposium on Space Nuclear Power Systems, Jan. 1990.Applicant
“Survey, Applications, And Prospects of Johnson Noise Thermometry,” by T. Blalock et al., Electrical Engineering Department, 1981 pp. 2-11.Applicant
“Noise Thermometry for Industrial and Metrological Applications at KFA Julich,” by H. Brixy et al., 7th International Symposium on Temperature, 1992.Applicant
“Johnson Noise Power Thermometer and its Application in Process Temperature Measurement,” by T.V. Blalock et al., American Institute of Physics 1982, pp. 1249-1259.Applicant
“In Situ Calibration of Nuclear Plant Platinum Resistance Thermometers Using Johnson Noise Methods,” EPRI, Jun. 1983.Applicant
“Johnson Noise Thermometer for High Radiation and High-Temperature Environments,” by L. Oakes et al., Fifth Symposium on Space Nuclear Power Systems, Jan. 1988, pp. 2-23.Applicant
“Development of a Resistance Thermometer For Use Up to 1600° C”, by M.J. de Groot et al., CAL LAB, Jul./Aug. 1996, pp. 38-41.Applicant
“Application of Neural Computing Paradigms for Signal Validation,” by B.R. Upadhyaya et al., Department of Nuclear Engineering, pp. 1-18.Applicant
“Application of Neural Networks for Sensor Validation and Plant Monitoring,” by B. Upadhyaya et al., Nuclear Technology, vol. 97, No. 2, Feb. 1992 pp. 170-176.Applicant
“Automated Generation of Nonlinear System Characterization for Sensor Failure Detection,” by B.R. Upadhyaya et al., ISA, 1989 pp. 269-274.Applicant
“A Decade of Progress in High Temperature Johnson Noise Thermometry,” by T.V. Blalock et al., American Institute of Physics, 1982 pp. 1219-1223.Applicant
“Detection of Hot Spots in Thin Metal Films Using an Ultra Sensitive Dual Channel Noise Measurement System,” by G.H. Massiha et al., Energy and Information Technologies in the Southeast, vol. 3 of 3, Apr. 1989, pp. 1310-1314.Applicant
“Detecting Blockage in Process Connections of Differential Pressure Transmitters”, by E. Taya et al., SICE, 1995, pp. 1605-1608.Applicant
“Development and Application of Neural Network Algorithms For Process Diagnostics,” by B.R. Upadhyaya et al., Proceedings of the 29th Conference on Decision and Control, 1990, pp. 3277-3282.Applicant
“A Fault-Tolerant Interface for Self-Validating Sensors”, by M.P. Henry, Colliquium, pp. 3/1-3/2 (Nov. 1990).Applicant
“Fuzzy Logic and Artificial Neural Networks for Nuclear Power Plant Applications,” by R.C. Berkan et al., Proceedings of the American Power Conference.Applicant
“Fuzzy Logic and Neural Network Applications to Fault Diagnosis”, by P. Frank et al., International Journal of Approximate Reasoning, (1997), pp. 68-88.Applicant
“Keynote Paper: Hardware Compilation-A New Technique for Rapid Prototyping of Digital Systems-Applied to Sensor Validation”, by M.P. Henry, Control Eng. Practice, vol. 3, No. 7., pp. 907-924, (1995).Applicant
“The Implications of Digital Communications on Sensor Validation”, by M. Henry et al., Report No. QUEL 1912/92, (1992).Applicant
“In-Situ Response Time Testing of Thermocouples”, ISA, by H.M. Hashemian et al., Paper No. 89-0056, pp. 587-593, (1989).Applicant
“An Integrated Architecture For Signal Validation in Power Plants,” by B.R. Upadhyaya et al., Third IEEE International Symposium on Intelligent Control, Aug. 24-26, 1988, pp. 1-6.Applicant
“Integration of Multiple Signal Validation Modules for Sensor Monitoring,” by B. Upadhyaya et al., Department of Nuclear Engineering, Jul. 8, 1990, pp. 1-6.Applicant
“Intelligent Behaviour for Self-Validating Sensors”, by M.P. Henry, Advances In Measurement, pp. 1-7, (May 1990).Applicant
“Measurement of the Temperature Fluctuation in a Resistor Generating 1/F Fluctuation,” by S. Hashiguchi, Japanese Journal of Applied Physics, vol. 22, No. 5, Part 2, May 1983, pp. L284-L286.Applicant
“Check of Semiconductor Thermal Resistance Elements by the Method of Noise Thermometry”, by A. B. Kisilevskii et al., Measurement Techniques, vol. 25, No. 3, Mar. 1982, New York, USA, pp. 244-246.Applicant
“Neural Networks for Sensor Validation and Plant Monitoring,” by B. Upadhyaya, International Fast Reactor Safety Meeting, Aug. 12-16, 1990, pp. 2-10.Applicant
“Neural Networks for Sensor Validation and Plantwide Monitoring,” by E. Eryurek, 1992.Applicant
“A New Method of Johnson Noise Thermometry”, by C.J. Borkowski et al., Rev. Sci. Instrum., vol. 45, No. 2, (Feb. 1974) pp. 151-162.Applicant
Parallel, Fault-Tolerant Control and Diagnostics System for Feedwater Regulation in PWRS, by E. Eryurek et al., Proceedings of the American Power Conference.Applicant
“Programmable Hardware Architectures for Sensor Validation”, by M.P. Henry et al., Control Eng. Practice, vol. 4, No. 10., pp. 1339-1354, (1996).Applicant
“Sensor Validation for Power Plants Using Adaptive Backpropagation Neural Network,” IEEE Transactions on Nuclear Science, vol. 37, No. 2, by E. Eryurek et al. Apr. 1990, pp. 1040-1047.Applicant
“Signal Processing, Data Handling and Communications: The Case for Measurement Validation”, by M.P. Henry, Department of Engineering Science, Oxford University.Applicant
“Smart Temperature Measurement in the '90s”, by T. Kerlin et al., C&I, (1990).Applicant
“Software-Based Fault-Tolerant Control Design for Improved Power Plant Operation,” IEEE/IFAC Joint Symposium on Computer-Aided Control System Design, Mar. 7-9, 1994 pp. 585-590.Applicant
A Standard Interface for Self-Validating Sensors, by M.P. Henry et al., Report No. QUEL 1884/91, (1991).Applicant
“Taking Full Advantage of Smart Transmitter Technology Now,” by G. Orrison, Control Engineering, vol. 42, No. 1, Jan. 1995.Applicant
“Using Artificial Neural Networks to Identify Nuclear Power Plant States,” by Israel E. Alguindigue et al., pp. 1-4.Applicant
“On-Line Statistical Process Control for a Glass Tank Ingredient Scale,” by R.A. Weisman, IFAC real Time Programming, 1985, pp. 29-38.Applicant
“The Performance of Control Charts for Monitoring Process Variation,” by C. Lowry et al., Commun. Statis.—Simula., 1995, pp. 409-437.Applicant
“A Knowledge-Based Approach for Detection and Diagnosis of Out-Of-Control Events in Manufacturing Processes,” by P. Love et al., IEEE, 1989, pp. 736-741.Applicant
“A TCP/IP Tutorial” by, Socolofsky et al., Spider Systems Limited, Jan. 1991 pp. 1-23.Applicant
“Approval Standards For Explosionproof Electrical Equipment General Requirements”, Factory Mutual Research, Cl. No. 3615, Mar. 1989, pp. 1-34.Applicant
“Approval Standard Intrinsically Safe Apparatus and Associated Apparatus For Use In Class I, II, and III, Division 1 Hazardous (Classified) Locations”, Factory Mutual Research, Cl. No. 3610, Oct. 1988, pp. 1-70.Applicant
“Automation On-line” by, Phillips et al., Plant Services, Jul. 1997, pp. 41-45.Applicant
“Climb to New Heights by Controlling your PLCs Over the Internet” by, Phillips et al., Intech, Aug. 1998, pp. 50-51.Applicant
“CompProcessor For Piezoresistive Sensors” MCA Technologies Inc. (MCA7707), pp. 1-8.Applicant
“Ethernet emerges as viable, inexpensive fieldbus”, Paul G. Schreier, Personal Engineering, Dec. 1997, p. 23-29.Applicant
“Ethernet Rules Closed-loop System” by, Eidson et al., Intech, Jun. 1998, pp. 39-42.Applicant
“Fieldbus Standard for Use in Industrial Control Systems Part 2: Physical Layer Specification and Service Definition”, ISA-S50.02-1992, pp. 1-93.Applicant
“Fieldbus Standard for Use in Industrial Control Systems Part 3: Data Link Service Definition”, ISA-S50.02-1997, Part 3, Aug. 1997, pp. 1-159.Applicant
Fieldbus Standard For Use in Industrial Control Systems Part 4: Data Link Protocol Specification, ISA-S50.02-1997, Part 4, Aug. 1997, pp. 1-148.Applicant
“Fieldbus Support For Process Analysis” by, Blevins et al., Fisher-Rosemount Systems, Inc., 1995, pp. 121-128.Applicant
“Fieldbus Technical Overview Understanding FOUNDATION™ fieldbus technology”, Fisher-Rosemount, 1998, pp. 1-23.Applicant
“Hypertext Transfer Protocol—HTTP/1.0” by, Berners-Lee et al., MIT/LCS, May 1996, pp. 1-54.Applicant
“Infranets, Intranets, and the Internet” by, Pradip Madan, Echelon Corp, Sensors, Mar. 1997, pp. 46-50.Applicant
“Internet Technology Adoption into Automation” by, Fondl et al., Automation Business, pp. 1-5.Applicant
“Internet Protocol Darpa Internet Program Protocol Specification” by, Information Sciences Institute, University of Southern California, RFC 791, Sep. 1981, pp. 1-43.Applicant
“Introduction to Emit”, emWare, Inc., 1997, pp. 1-22.Applicant
“Introduction to the Internet Procotols” by, Charles L. Hedrick, Computer Science Facilities Group, Rutgers University, Oct. 3, 1988, pp. 1-97.Applicant
“Is There A Future For Ethernet in Industrial Control?”, Miclot et al., Plant Engineering, Oct. 1988, pp. 44-46, 48, 50.Applicant
LFM/SIMA Internet Remote Diagnostics Research Project Summary Report, Stanford University, Jan. 23, 1997, pp. 1-6.Applicant
“Managing Devices with the Web” by, Howard et al., Byte, Sep. 1997, pp. 45-64.Applicant
“Modular Microkernel Links GUI And Browser For Embedded Web Devices” by, Tom Williams, pp. 1-2.Applicant
“PC Software Gets Its Edge From Windows, Components, and the Internet”, Wayne Labs, I&CS, Mar. 1997, pp. 23-32.Applicant
Proceedings Sensor Expo, Aneheim, California, Produced by Expocon Managemnet Associates, Inc., Apr. 1996, pp. 9-21.Applicant
Proceedings Sensor Expo, Boston, Massachuttes, Produced by Expocon Management Associates, Inc., May 1997, pp. 1-416.Applicant
“Smart Sensor Network of the Future” by, Jay Warrior, Sensors, Mar. 1997, pp. 40-45.Applicant
“The Embedded Web Site” by, John R. Hines, IEEE Spectrum, Sep. 1996, p. 23.Applicant
“Transmission Control Protocol: Darpa Internet Program Protocol Specification” Information Sciences Institute, Sep. 1981, pp. 1-78.Applicant
“Transmission Control Protocol DARPA Internet Program Procotol Specification”, by Information Sciences Institute University of Southern California, pp. 1-78, Sep. 1981.Applicant
“Advanced Engine Diagnostics Using Universal Process Modeling”, by P. O'Sullivan, Presented at the 1996 SAE Conference on Future Transportation Technology, pp. 1-9, 1996.Applicant
“Thermocouple Continuity Checker”, IBM Technical Disclosure Bulletin, vol. 20, No. 5, Oct. 1977.Applicant
“Self-Validating Thermocouple”, by J. Yang et al., IEEE, pp. 239-253, 1997.Applicant
“Instrument Engineers' Handbook”, Process Measurement, pp. 266-333, 1969, 1982.Applicant
“The IEEE P1451.1 Object Model Network Independent Interfaces for Sensors and Actuators”, by J. Warrior, pp. 1-14, 1997.Applicant
“The Collision Between the Web and Plant Floor Automation”, by J. Warrior, 1997.Applicant
“Microsoft Press Computer Dictionary”, p. 184, 1997.Applicant
“emWare's New Licensing Structure Lets You Pay For Networking and Internet Capability Only When You Use It”, 3 pages from the Internet, Nov. 4, 1998.Applicant
U.S. application No. 09/169,873, Eryurek et al., filed Oct. 12, 1998.Applicant
U.S. application No. 09/303,869, Eryurek et al., filed May 3, 1999.Applicant
U.S. application No. 09/257,896, Eryurek et al., filed Feb. 25, 1999.Applicant
U.S. application No. 09/335,212, Kirkpatrick et al., filed Jun. 17, 1999.Applicant
U.S. application No. 09/344,631, Eryurek et al., filed Jun. 25, 1999.Applicant
U.S. application No. 09/360,473, Eryurek et al., filed Jul. 23, 1999.Applicant
U.S. application No. 09/369,530, Eryurek et al., filed Aug. 6, 1999.Applicant
U.S. application No. 09/383,828, Eryurek et al., filed Aug. 27, 1999.Applicant
U.S. application No. 09/384,876, Eryurek et al., filed Aug. 27, 1999.Applicant
U.S. application No. 09/406,263, Kirkpatrick et al., filed Sep. 24, 1999.Applicant
U.S. application No. 09/409,098, Eryurek et al., filed Sep. 30, 1999.Applicant
U.S. application No. 09/409,114, Eryurek et al., filed Sep. 30, 1999.Applicant
U.S. application No. 09/565,604, Eryurek et al., filed May 4, 2000.Applicant
U.S. application No. 09/576,450, Wehrs, filed May 30, 2000.Applicant
U.S. application No. 09/606,259, Eryurek, filed Jun. 29, 2000.Applicant
U.S. application No. 09/616,118, Eryurek et al., filed Jul. 14, 2000.Applicant
U.S. application No. 09/627,543, Eryurek et al., filed Jul. 28, 2000.Applicant
“Internal Statistical Quality Control for Quality Monitoring Instruments”, by P. Girling et al., ISA, 15 pgs., 1999.Applicant
Web Pages from www.triant.com (3 pgs.).Applicant
“Statistical Process Control (Practice Guide Series Book)”, Instrument Society of America, 1995, pp. 1-58 and 169-204.Applicant
“Time-Frequency Analysis of Transient Pressure Signals for a Mechanical Heart Valve Cavitation Study,” ASAIO Journal, by Alex A. Yu et al., vol. 44, No. 5, pp. M475-M479, (Sep—Oct. 1998).Applicant
“Transient Pressure Signals in Mechanical Heart Valve Caviation,” by Z.J. Wu et al., pp. M555-M561 (undated).Applicant
“Caviation in Pumps, Pipes and Valves,” Process Engineering, by Dr. Ronald Young, pp. 47 and 49 (Jan. 1990).Applicant
“Quantification of Heart Valve Cavitation Based on High Fidelity Pressure Measurements,” Advances in Bioengineering 1994, by Laura A. Garrison et al., BED-vol. 28, pp. 297-298 (Nov. 6-11, 1994).Applicant
“Monitoring and Diagnosis of Cavitation in Pumps and Valves Using the Wigner Distribution,” Hydroaccoustic Facilities, Instrumentation, and Experimental Techniques, NCA-vol. 10, pp. 31-36 pp. (1991).Applicant
“Developing Predictive Models for Cavitation Erosion,” Codes and Standards in A Global Environment, PVP-vol. 259, pp. 189-192 (1993).Applicant
“Self-Diagnosing Intelligent Motors: A Key Enabler for Next Generation Manufacturing System,” by Fred M. Discenzo et al., pp. 3/1-3/4 (1999).Applicant
U.S. application No. 09/576,719, Coursolle et al., filed May 23, 2000.Applicant
U.S. application No. 09/799,824, Rome et al., filed Mar. 5, 2001.Applicant
“A Microcomputer-Based Instrument for Applications in Platinum Resistance Thermomety,” by H. Rosemary Taylor and Hector A. Navarro, Journal of Physics E. Scientific Instrument, vol. 16, No. 11, pp. 1100-1104 (1983).Applicant
“Experience in Using Estelle for the Specification and Verification of a Fieldbus Protocol: FIP,” by Barretto et al., Computer Networking, pp. 295-304 (1990).Applicant
“Computer Simulation of H1 Field Bus Transmission,” by Utsumi et al., Advances in Instrumentation and Control, vol. 46, Part 2, pp. 1815-1827 (1991).Applicant
“Progress in Fieldbus Developments for Measuring and Control Application,” by A. Schwaier, Sensor and Acuators, pp. 115-119 (1991).Applicant
“Ein Emulationssystem zur Leistungsanalyse von Feldbussystemen, Teil 1,” by R. Hoyer, pp. 335-336 (1991).Applicant
“Simulatore Integrato: Controllo su bus di campo,” by Barabino et al., Automazione e Strumentazione, pp. 85-91 (Oct. 1993).Applicant
“Ein Modulares, verteiltes Diagnose-Expertensystem für die Fehlerdiagnose in lokalen Netzen,” by Jürgen M. Schröder, pp. 557-565 (1990).Applicant
“Fault Diagnosis of Fieldbus Systems,” by Jürgen Quade, pp. 577-581 (10/92).Applicant
“Ziele und Anwendungen von Feldbussystemen,” by T. Pfeifer et al., pp. 549-557 (10/87).Applicant
“PROFIBUS-Infrastrukturmaβnahmen,” by Tilo Pfeifer et al., pp. 416-419 (8/91).Applicant
“Simulation des Zeitverhaltens von Feldbussystemen,” by O. Schnelle, pp. 440-442 (1991).Applicant
“Modélisation et simulation d'un bus de terrain: FIP,” by Song et al, pp. 5-9 (undated).Applicant
“Feldbusnetz für Automatisierungssysteme mit intelligenten Funktionseinheiten,” by W. Kriesel et al., pp. 486-489 (1987).Applicant
“Bus de campo para la inteconexión del proceso con sistemas digitales de control,” Tecnología, pp. 141-147 (1990).Applicant
“Dezentrale Installation mit Echtzeit-Feldbus,” Netzwerke, Jg. Nr.3 v. 14.3, 4 pages (1990).Applicant
“Process Measurement and Analysis,” by Liptak et al., Instrument Engineers' Handbook, Third Edition, pp. 528-530, (1995).Applicant
“Improving Dynamic Performance of Temperature Sensors With Fuzzy Control Techniques,” by Wang Lei et al., pp. 872-873 (1992).Applicant
“Microsoft Press Computer Dictionary” 2nd Edition, 1994, Microsoft Press. p. 156.Applicant
Journal of Intelligent Manufacturing (1997) 8, 271-276 article entitled “On-line tool condition monitoring system with wavelet fuzzy neural network”.Applicant
“Notification of Transmittal of the International Search Report or the Declaration” for PCT/US01/40791.Applicant
“Notification of Transmittal of the International Search Report or the Declaration” for PCT/US01/40782.Applicant
IEEE Transactions on Magnetics, vol. 34, No. 5, Sep. 1998, “Optimal Design of the Coils of an Electromagnetic Flow Meter,” pp. 2563-2566.Applicant
IEEE Transactions on Magnetics, vol. 30, No. 2, Mar. 1994, “Magnetic Fluid Flow Meter for Gases,” pp. 936-938.Applicant
IEEE Instrumentation and Measurement Technology Conference, May 18-21, 1998, “New approach to a main error estimation for primary transducer of electromagnetic flow meter,” pp. 1093-1097.Applicant
School of Engineering and Applied Sciences, by J.E. Amadi-Echendu and E. H. Higham, “Additional Information from Flowmeters via Signal Analysis,” pp. 187-193.Applicant

Abstract

Description

Background of the Invention

Summary of the Invention

Brief Description of the Drawings

[0008] FIG. 1 shows a process control system including a transmitter in accordance with the present invention.

[0009] FIG. 2 is a block diagram of a transmitter of the present invention.

[0010] FIG. 3 is a simplified block diagram of a transmitter in accordance with one embodiment of the invention.

[0011] FIG. 4 is a simplified block diagram in accordance with an embodiment of the present invention.

Detailed Description of the Preferred Embodiments

\begin{matrix} SHI = \frac{R_{1} - R_{2}}{P_{1} - P_{2}} & Eq . 1 \end{matrix}

[0022] Microprocessor 52 employs the following equation to compute the temperature of RTD sensor element 61:

\begin{matrix} R_{1} = \frac{V_{R1}}{V_{RREF}} (R_{REFNOM}) & Equation 2 \end{matrix}


	R	= resistance of RTD sensor element 61;
	V	= voltage drop across the RTD sensor element 61;
	V	= voltage drop across resistance R
	R	= nominal resistance of the reference resistance
		R

\begin{matrix} R (t) = R_{0} {1 + α (t - δ (\frac{t}{100}) (\frac{t}{100} - 1) - β (\frac{t}{100} - 1) {(\frac{t}{100})}^{3})} & Eq . 3 \end{matrix}