Process device with diagnostic annunciation

• US 20060069455A1
• Filed: 09/30/2004
• Published: 03/30/2006
• 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 J., Davis, Dale S.
• Granted Patent: US 7,991,582 B2
• Time in Patent Office: Days
• US Class Current: 700/45
• 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. A method is also provided.

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 configured to couple to the two-wire process control loop configured to provide an analog current output on the loop indicative of more than two diagnostic conditions.

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

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

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

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

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

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

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

protocol.

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

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

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

13. The apparatus 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 apparatus of claim 1 wherein the analog current output is changed over time in a predetermined pattern indicative of a diagnostic condition.

15. The apparatus of claim 1 wherein the analog current level comprises a semi-continuous value.

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 indicative of a diagnostic condition and having a value of between 4 milliAmps and 20 milliAmps.

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

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

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

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

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

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

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

protocol.

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

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

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

28. The apparatus 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 apparatus of claim 16 wherein the analog current output is changed over time in a predetermined pattern indicative of a diagnostic condition.

30. The apparatus of claim 16 wherein the analog current level comprises a semi-continuous value.

31. 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 configured to couple to the two-wire process control loop configured to provide an analog current output on the loop indicative of predictive diagnostic information.

32. The apparatus of claim 31 wherein the loop analog current output has a value of between 4 mA and 20 mA.

33. The apparatus of claim 31 wherein the process device is a process variable transmitter.

34. The apparatus of claim 31 wherein the process device is a process controller.

35. The apparatus of claim 31 wherein the process device is configured for use in a Safety Instrumented System.

36. The apparatus of claim 31 wherein the process device is completely powered with power received through the process control loop.

37. The apparatus of claim 31 wherein the process control loop operates in accordance with the HART®

protocol.

38. The apparatus of claim 31 wherein the diagnostic conditions are related to standard diagnostic conditions which are mapped to particular current levels.

39. The apparatus of claim 31 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.

40. The apparatus of claim 31 wherein circuitry of the process device is completely powered with power received through the second process control loop.

41. The apparatus of claim 31 wherein circuitry associated with at least one of the output and the second output is configured to power off during periods of inactivity.

42. The apparatus of claim 41 wherein circuitry of the process device is completely powered with power received from the two-wire process control loop.

43. The apparatus of claim 31 wherein the diagnostic circuitry is implemented in a feature module which is coupled to a sensor module of the process device.

44. The apparatus of claim 31 wherein the analog current output is changed over time in a predetermined pattern indicative of a diagnostic condition.

45. The apparatus of claim 31 wherein the analog current level comprises a semi-continuous value.

46. Interface circuitry for use in diagnostics of an industrial process, comprising:

a first loop connection configured to couple to a first two wire process control loop which couples to a process device, the first two wire process control loop configured to carry information related to a diagnostic condition and to a process variable;

a second loop connection configured to couple to a second process control loop, wherein the interface circuitry controls a current level in the second process control loop as a function of the process variable; and

a third loop connection configured to couple to a third process control loop, wherein the interface circuitry controls a current level in the third process control loop as a function of the diagnostic condition.

47. The apparatus of claim 46 wherein the interface circuitry is located in a control room.

48. The apparatus of claim 46 wherein the interface circuitry is located in a non-hazardous area.

49. The apparatus of claim 46 wherein the interface circuitry is located in a hazardous area and meets intrinsic safety standards.

50. The apparatus of claim 46 wherein the interface circuitry maps various diagnostic conditions to the current level carried in the third process control loop.

51. The apparatus of claim 46 wherein the current level in the third process control loop comprises a semi-continuous value indicative of diagnostic conditions.

52. The apparatus of claim 46 wherein the current level in the third process control loop is controlled in accordance with a pattern indicative of a diagnostic condition.

53. The apparatus of claim 46 wherein the current level in the third process control loop is indicative of predictive diagnostic information.

54. The apparatus of claim 46 wherein the interface circuitry performs diagnostics.

55. The apparatus of claim 46 including a fourth loop connection to couple to a second process device.

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

diagnosing operation of the process device or the process;

outputting an analog current level on the two-wire process control loop indicative of more than two diagnostic conditions.

57. A method of annunciating diagnostic information related to a process or a process device 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 indicative of a diagnostic condition and having a value of between 4 milliAmps and 20 milliAmps.

58. A method of annunciating diagnostic information related to a process or a process device 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 indicative of predictive diagnostic information.