Transmitter with software for determining when to initiate diagnostics

• US 6,532,392 B1
• Filed: 07/28/2000
• Issued: 03/11/2003
• Est. Priority Date: 03/28/1996
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Warrior, Jogesh, Esboldt, Steven R., Eryurek, Evren
• Primary Examiner(s): Follansbee, John A.
• Assistant Examiner(s): BARNES-BULLOCK, CRYSTAL JOY
• Application Number:
  US09/627,543
• Time in Patent Office: 956 Days
• Field of Search: 700/30, 700/31, 700/33, 700/46, 700/54, 318/561
• US Class Current: 700/54
• CPC Class Codes: G05B 13/0275 using fuzzy logic only
• CPC Class Codes: G05B 21/02 electric
• CPC Class Codes: G05B 23/0221 Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods
• CPC Class Codes: G05B 23/0278 Qualitative, e.g. if-then rules; Fuzzy logic; Lookup tables; Symptomatic search; FMEA

Abstract

A process device couples to a process control loop. The process device receives a process signal. A memory in the process device contains a nominal parameter value. Computing circuitry provides an event output based upon the stored nominal value and the process signal. Output circuitry provides an output in response to the event output.

Claims

1. A process device coupled to a process control loop, comprising:

a process signal input for providing a batch process signal related to a batch process;

memory containing a nominal parameter value related to a nominal change for the batch process signal;

computing circuitry providing an event output in response to an event in the batch process, the event detected when a difference between the batch process signal and the nominal parameter value is more than a maximum amount;

output circuitry outputting the event output;

wherein the process control loop is selected from the group consisting of two wire process control loops, three wire process control loops and four wire process control loops.

2. The process device of claim 1 wherein the device is completely powered with power received from the process control loop.

3. The process device of claim 1 wherein the process signal input comprises a sensor input channel and the process signal comprises a batch process variable.

4. The process device of claim 3 wherein the process variable is selected from the group consisting of pressure, temperature, pH, flow, turbidity, level, position, conductivity, motor current, motor back emf and vibration.

5. The process device of claim 1 wherein the process signal input comprises a control channel and the process signal comprises a control signal.

6. The process device of claim 1 wherein the process signal input comprises input circuitry coupled to the control loop to receive the process signal from the process control loop.

7. The process device of claim 1 wherein the batch process signal changes from a substantially increasing value to a substantially constant value at a transition point and the nominal parameter value is related to an angle in the batch process signal at the transition point.

8. The process device of claim 1 wherein the batch process signal changes from a substantially constant value to a substantially decreasing value at a transition point and the nominal parameter value is related to an angle in the batch process signal at the transition point.

9. The process device of claim 1 wherein the nominal parameter value is related to a nominal rate of change (ROC) of the batch process signal.

10. A method in a process device coupled to a process control loop, comprising:

receiving a process signal related to a batch process;

retrieving a nominal parameter value related to a nominal change for the batch process signal stored in a memory;

detecting an event in the batch process detected when a difference between the batch process signal and the nominal parameter value is more than a maximum amount;

providing an output indicative of the detected event;

wherein the process control loop is selected from the group consisting of two wire process control loops, three wire process control loops and four wire process control loops.

11. The method of claim 10 including completely powering the device with power received from the process control loop.

12. The method of claim 10 wherein the process signal comprises a batch process variable.

13. The method of claim 12 wherein the process variable is selected from the group consisting of pressure, temperature, pH, flow, turbidity, level, position, conductivity, motor current, motor back emf and vibration.

14. The method of claim 10 wherein the process signal comprises a control signal.

15. The method of claim 10 wherein the batch process signal changes from a substantially increasing value to a substantially constant value at a transition point and the nominal parameter value is related to an angle in the batch process signal at the transition point.

16. The method of claim 10 wherein the batch process signal changes from a substantially constant value to a substantially decreasing value at a transition point and the nominal parameter value is related to an angle in the batch process signal at the transition point.

17. The method of claim 10 wherein the nominal parameter value is related to a nominal rate of change (ROC) of the batch process signal.

18. A process device coupled to a process control loop, comprising:

a process signal input providing a process signal comprising a process variable related to a process wherein the process variable is selected from the group consisting of pressure, temperature, pH, flow, turbidity, level, position, conductivity, motor current, motor back emf and vibration;

memory containing a nominal parameter value;

computing circuitry providing an event output in response to an event in the process, the event detected based upon the process signal and the nominal parameter value, the computing circuitry providing the event output when the process has stabilized after initialization;

output circuitry outputting the event output;

wherein the process control loop is selected from the group consisting of two wire process control loops, three wire process control loops and four wire process control loops.

19. The process device of claim 18 wherein process stabilization is determined by monitoring a rate of change of a statistical parameter of the process variable.

20. The process device of claim 19 wherein the statistical parameter comprises RMS.

21. The process device of claim 19 wherein the statistical parameter comprises standard deviation.

22. The process device of claim 19 wherein process stabilization is determined if the rate of change of the statistical parameter is less than about 2% of a span of the process variable.

23. The process device of claim 18 wherein the device is completely powered with power received from the process control loop.