Process device with supervisory overlayer

• US 8,180,466 B2
• Filed: 11/21/2003
• Issued: 05/15/2012
• Est. Priority Date: 11/21/2003
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Longsdorf, Randy, Davis, Dale, Hedtke, Robert, Nelson, Scott
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): Norton, Jennifer L
• Application Number:
  US10/719,163
• Publication Number:
  US 20050113942A1
• Time in Patent Office: 3,098 Days
• Field of Search: 700/79, 700/51, 700/140, 700/80, 477/5, 324/718, 324/713, 702/33, 702/104, 702/122, 702/182, 702/183, 702/188, 709/250
• US Class Current: 700/79
• CPC Class Codes: G05B 19/0425 Safety, monitoring
• CPC Class Codes: G05B 2219/24008 Safety integrity level, safety integrated systems SIL SIS
• CPC Class Codes: G05B 2219/24125 Watchdog, check at timed intervals
• CPC Class Codes: G05B 2219/25006 Interface connected to fieldbus
• CPC Class Codes: G05B 2219/25014 Fieldbus general name of bus connected to machines, detectors, actuators
• CPC Class Codes: G05B 2219/25428 Field device
• CPC Class Codes: G05B 9/02 electric

Abstract

A process device is configured to meet a desired Safety Integrity Level (SIL). A device interface is configured to couple to the process device and provide an output related to operation of a component of the process device. A component monitor monitors operation of the component and identifies a safety event of the component. A safety response module responds to a safety event of the component in accordance with a safety response.

Claims

1. A process device for measuring a process variable of an industrial process, comprising:

a process variable sensor configured to sense the process variable;

device circuitry coupled to the process variable sensor configured to process an output from the process variable sensor and provide an output related to the sensed process variable;

a databus configured to carry data between at least two components of the process device, the two components contained within the process device;

safety response circuitry contained within the process device and which is separate from the two components, the safety response circuitry comprising;

a device interface to couple to the process device and provide an output related to operation of a component of the process device, wherein the device interface comprises a connection to the databus of the process device which is used to transfer digital data between the at least two components of the device and a microprocessor of the device;

a component monitor to monitor data carried on the databus, and monitor operation of the component of the process device based upon the output from the device interface and responsively identify a safety event of the component indicative of a failure of the component and provide a safety event output; and

a safety response module to respond to the safety event of the component based upon the safety event output in accordance with a safety response; and

wherein the device interface, component monitor and safety response module are isolated from other components of the process device to provide redundancy.

2. The apparatus of claim 1 wherein the device interface comprises a sensor coupled to the process device.

3. The apparatus of claim 2 wherein the process device couples to a process control loop and the sensor monitors current flow in the process control loop.

4. The apparatus of claim 3 wherein the component monitor compares the sensed current with a current value.

5. The apparatus of claim 1 wherein the safety response module controls the current in a process control loop based upon a safety failure.

6. The apparatus of claim 1 wherein the device interface comprises a watch dog circuit.

7. The apparatus of claim 1 wherein the device interface senses power drawn by circuitry of the process device.

8. The apparatus of claim 1 wherein the device interface couples to a memory.

9. The apparatus of claim 8 wherein the component monitor detects errors in the data stored in the memory.

10. The apparatus of claim 1 wherein the safety response module provides an alarm output.

11. The apparatus of claim 1 wherein the safety response module disconnects the process device from a process control loop.

12. The apparatus of claim 1 wherein the safety response module disconnects circuitry in the process device.

13. The apparatus of claim 1 wherein the safety response module attempts to compensate for the safety failure.

14. The apparatus of claim 12 wherein the safety response module corrects for errors in data in the device.

15. The apparatus of claim 14 wherein the safety response module interpolates between data points in order to correct a data error.

16. The apparatus of claim 14 wherein the safety response module holds a previous data point.

17. The apparatus of claim 2 wherein the sensor comprises a voltage sensor.

18. The apparatus of claim 2 wherein the sensor comprises a current sensor.

19. The apparatus of claim 1 wherein the device interface monitors data carried in a databus of the device.

20. The apparatus of claim 1 wherein the component monitor comprises software implemented in a microprocessor of the device.

21. The apparatus of claim 1 wherein the safety event comprises a possibility of a future component failure.

22. The apparatus of claim 1 wherein the safety event comprises a detection of a component failure.

23. The apparatus of claim 1 wherein the safety response module is implemented in a feature module which couples to a sensor module of the process device.

24. The apparatus of claim 1 wherein the safety response module is implemented in a feature module which couples to a plurality of sensor modules.

25. The apparatus of claim 23 wherein the component monitor monitors data from a sensor in the sensor module.

26. The apparatus of claim 1 including a display and wherein the component monitors data sent to the display.

27. The apparatus of claim 1 wherein the component monitor monitors a plurality of process devices.

28. The apparatus of claim 1 wherein the component monitor and safety response module are implemented in software.

29. The apparatus of claim 28 wherein the software upgrades an existing process device.