Process device with diagnostic annunciation

• US 7,991,582 B2
• Filed: 09/30/2004
• Issued: 08/02/2011
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Longsdorf, Randy, Davis, Dale
• Primary Examiner(s): Wachsman; Hal D
• Application Number:
  US10/955,790
• Publication Number:
  US 20060069455A1
• Time in Patent Office: 2,497 Days
• Field of Search: 702/183, 702/64, 702/188
• US Class Current: 702/183
• CPC Class Codes: G05B 23/027 Alarm generation, e.g. communication protocol; Forms of alarm

Abstract

A process device for coupling to a two-wire process control loop—includes diagnostic circuitry configured to identify a failure or reduced level of performance or provide a prediction of a future failure or reduced level of performance. An output coupled to the two-wire process control loop is configured to provide an analog output on the loop related to an output from the diagnostic circuitry.

Claims

1. A process device for coupling to a two-wire process control loop comprising:

diagnostic circuitry configured to diagnose operation of the process device or the process;

an output responsive to the diagnostic circuitry configured to couple to the two-wire process control loop configured to provide an analog current output on the loop, wherein the analog current level has a first value indicative of a first diagnostic condition, a second value indicative of a second diagnostic condition, and a third value indicative of a third diagnostic condition, wherein the first, second and third values are indicative of diagnostic conditions and not a process variable.

2. The process device of claim 1 wherein the loop analog current output is between 4 mA and 20 mA.

3. The process device of claim 1 wherein the loop analog current output is indicative of predictive diagnostic information.

4. The process device of claim 1 wherein the process device comprises a process variable transmitter.

5. The process device of claim 1 wherein the process device comprises a process controller.

6. The process device of claim 1 wherein the process device is configured for use in a Safety Instrumented System.

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

8. The process device of claim 1 wherein the process control loop operates in accordance with the HART®

protocol.

9. The process device of claim 1 wherein the diagnostic conditions are related to standardized diagnostic conditions which are mapped to particular current levels.

10. The process device of claim 1 including a second process control loop including a second output configured to couple to a second two-wire process control loop, the second output related to a sensed process variable.

11. The process device of claim 10 wherein circuitry of the process device is completely powered with power received through the second process control loop.

12. The process device of claim 10 wherein circuitry associated with at least one of the analog current output and the second output is configured to power off during periods of inactivity.

13. The process device of claim 1 wherein the diagnostic circuitry is implemented in a feature module which is coupled to a sensor module of the process device.

14. The process device of claim 1 wherein the analog current output is changed between values over time in a pre-determined pattern indicative of a diagnostic condition.

15. The process device of claim 1 wherein the analog current output comprises a semi-continuous current level.

16. A process device for coupling to a two-wire process control loop comprising:

diagnostic circuitry configured to diagnose operation of the process device or process;

an output configured to couple to the two-wire process control loop configured to provide an analog current output on the loop in response to diagnosed operation of the process device or process, wherein the analog current level has a first value indicative of a first diagnostic condition, a second value indicative of a second diagnostic condition, and a third value indicative of a third diagnostic condition and having a value of between 4 milliAmps and 20 milliAmps, wherein the first, second and third values are indicative of diagnostic conditions and not a process variable.

17. The process device of claim 16 wherein the loop analog current output is indicative of more than two diagnostic conditions.

18. The process device of claim 16 wherein the loop analog current output is indicative of predictive diagnostic information.

19. The process device of claim 16 wherein the process device comprises a process variable transmitter.

20. The process device of claim 16 wherein the process device comprises a process controller.

21. The process device of claim 16 wherein the process device is configured for use in a Safety Instrumented System.

22. The process device of claim 16 wherein the process device is completely powered with power received through the process control loop.

23. The process device of claim 16 wherein the process control loop operates in accordance with the HART®

protocol.

24. The process device of claim 16 wherein the diagnostic conditions are related to standard diagnostic conditions which are mapped to particular current levels.

25. The process device of claim 16 including a second process control loop including a second output configured to couple to a second two-wire process control loop, the second output related to a sensed process variable.

26. The process device of claim 25 wherein circuitry of the process device is completely powered with power received through the second process control loop.

27. The process device of claim 25 wherein circuitry associated with at least one of the analog current output and the second output is configured to power off during periods of inactivity.

28. The process device of claim 16 wherein the diagnostic circuitry is implemented in a feature module which is coupled to a sensor module of the process device.

29. The process device of claim 16 wherein the analog current output is changed between values over time in a pre-determined pattern indicative of a diagnostic condition.

30. The process device of claim 16 wherein the analog current output comprises a semi-continuous current level.

31. A method of annunciating diagnostic information related to a process device or a process coupled to a two-wire process control loop comprising:

diagnosing operation of the process device or the process;

outputting an analog current level on the two-wire process control loop in response to diagnosed operation of the process device or process, wherein the analog current level has a first value indicative of a first diagnostic condition, a second value indicative of a second diagnostic condition, and a third value indicative of a third diagnostic condition, wherein the first, second and third values are indicative of diagnostic conditions and not a process variable.