PROCESS FIELD DEVICE WITH RADIO FREQUENCY COMMUNICATION

• US 20070285224A1
• Filed: 08/21/2007
• Published: 12/13/2007
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: Brian Westfield, Charles Willcox, David Broden, Kelly Orth, Robert Karschnia
• Original Assignee: Brian Westfield, Charles Willcox, David Broden, Kelly Orth, Robert Karschnia
• Inventors: Broden, David, Willcox, Charles, Karschnia, Robert, Orth, Kelly, Westfield, Brian
• Granted Patent: US 7,956,738 B2
• Time in Patent Office: Days
• US Class Current: 340/538
• CPC Class Codes: G05B 19/4185 characterised by the network communication
• CPC Class Codes: G05B 2219/33192 Radio link, wireless
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y02P 90/80 Management or planning

Abstract

A field device for use in an industrial process control or monitoring system includes terminals configured to connect to a two-wire process control loop. The loop carries data and provides power to the field device. RF circuitry in the field device is provided for radio frequency communication. A power supply powers the RF circuitry using power received from the two-wire process control loop.

Claims

1. A process control transmitter for monitoring a process variable in an industrial process comprising:

a process variable sensor configured to sense the process variable;

I/O circuitry configured to couple to a two wire process control loop and communicate on the process control loop;

wireless communication circuitry coupled to the two wire process control loop configured to transmit an RF signal; and

power supply circuitry coupled to the two wire process control loop including a voltage regulator coupled to an electrical element which is electronically connected in series with the process control loop, the voltage regulator configured to receive a voltage drop from the electrical element and responsively provide a regulated voltage output to power the wireless communication circuitry.

2. The apparatus of claim 1 including a terminal block configured to electronically connect to the two wire process control loop and wherein the wireless communication circuitry couples to the terminal block.

3. The apparatus of claim 1 wherein the wireless communication circuitry is completely powered with power from the two wire process control loop.

4. The apparatus of claim 1 wherein the wireless communication circuitry includes a resistor coupled in series with the two wire process control loop.

5. The apparatus of claim 1 including a battery configured to power the wireless communication circuitry.

6. The apparatus of claim 1 wherein the wireless communication circuitry includes two wire loop communication circuitry configured to communicate on the two wire communications loop.

7. The apparatus of claim 1 wherein the wireless communication circuitry includes HART®

communication circuitry.

8. The apparatus of claim 1 wherein the wireless communication circuitry includes intrinsic safety protection circuitry.

9. The apparatus of claim 1 wherein the wireless communication circuitry includes an analog to digital converter configured to provide a digital representation of current flowing through the two wire process control loop.

10. The apparatus of claim 8 wherein the RF signal is based upon the sensed current.

11. The apparatus of claim 1 wherein the wireless communication circuitry includes a microprocessor.

12. The apparatus of claim 1 wherein the wireless communication circuitry includes a memory containing addressing information.

13. The apparatus of claim 1 wherein the wireless communication circuitry includes an antenna.

14. The apparatus of claim 1 wherein the wireless communication circuitry is configured to receive an RF signal and responsively transmit a signal on the two wire process control loop.

15. The apparatus of claim 1 wherein the electrical element comprises a zener diode configured to couple in series with the two wire process control loop.

16. The apparatus of claim 1 wherein the wireless communication circuitry is configured to enter a sleep mode during idle periods.

17. The apparatus of claim 1 including:

an energy storage capacitor configured to store an electrical charge using power received from the two-wire process control loop; and

wherein the power supply circuitry is configured to use power from the electrical charge stored on the energy storage capacitor.

18. The apparatus of claim 1 wherein the wireless circuitry is carried on a modular circuit board configured to mount in a housing of the process variable transmitter.

19. The apparatus of claim 1 wherein the wireless communication circuitry includes terminals configured to couple in series with the two-wire process control loop.

20. The apparatus of claim 1 including:

an explosion proof housing configured to enclose the wireless circuitry;

an integral RF transparent region in the housing configured to allow RF transmission therethrough.

21. The apparatus of claim 20 wherein the RF transparent region comprises glass.

22. The apparatus of claim 20 including an end cap configured to mount to a main housing and wherein the end cap includes the RF transparent region.

23. The apparatus of claim 1 including:

a circuit board configured to carry the wireless communication circuitry; and

an RF antenna coupled to the wireless communication circuitry and carried on the wireless communication circuit board.

24. The apparatus of claim 19 wherein the wireless communication circuitry is integral with a terminal block which carries the terminals.

25. The apparatus of claim 1 wherein the wireless communication circuitry is configured to transmit an RF signal related to an analog current level carried through the process loop.

26. The apparatus of claim 1 wherein the wireless communication circuitry is configured to transmit an RF signal related to a digital signal carried by the process control loop.

27. The apparatus of claim 1 including a HART®

module coupled to the wireless communication circuitry configured to operate as a bi-directional HART®

to RF gateway unit.

28. The apparatus of claim 1 wherein the wireless communication circuitry is configured for periodic communication.

29. The apparatus of claim 1 wherein the wireless communication circuitry is configured to transmit an RF signal related to a process variable.

30. A field device for use in an industrial process control or monitoring system, comprising:

terminals configured to connect to a two-wire process control loop configured to carry data and to provide power;

radio frequency (RF) communication circuitry configured for radio frequency communication;

power supply circuitry configured to power the RF circuitry using power received from the two-wire process control loop;

an energy storage capacitor configured to store an electrical charge using power received from the two-wire process control loop;

wherein the power supply circuitry is configured to use power from the electrical charge stored on the energy storage capacitor; and

wherein the RF circuitry is configured for bi-directional communication.

31. The apparatus of claim 30 wherein the energy storage capacitor comprises a super capacitor.

32. The apparatus of claim 30 wherein the RF circuitry is configured to transmit RF data as a function of information received from the two-wire process control loop in accordance with the HART®

protocol.

33. The apparatus of claim 30 including a transducer or actuator configured to interact with an industrial process.

34. The apparatus of claim 33 wherein the RF circuitry including a modular circuit board which carries the RF circuitry, the modular circuit board configured to mount in a housing of the field device.

35. The apparatus of claim 30 wherein the RF circuitry is configured for digital communication.

36. The apparatus of claim 30 wherein the RF circuitry is configured for analog communication.

37. The apparatus of claim 30 wherein the terminals are configured to couple in series with the two-wire process control loop.

38. The apparatus of claim 30 including:

an explosion proof housing configured to enclose the RF circuitry; and

an integral RF transparent region in the housing configured to allow RF transmission therethrough.

39. The apparatus of claim 38 wherein the RF transparent region comprises glass.

40. The apparatus of claim 39 including an end cap configured to mount to a main housing and wherein the end cap includes the RF transparent region.

41. The apparatus of claim 30 including:

a circuit board configured to carry the RF circuitry; and

an RF antenna coupled to the RF circuitry and carried on the RF circuit board.

42. The apparatus of claim 30 wherein the RF circuitry is integral with a terminal block which carries the terminals.

43. The apparatus of claim 30 wherein the RF communication circuitry is configured to transmit an RF signal related to an analog current level carried through the process loop.

44. The apparatus of claim 30 wherein the RF communication circuitry is configured to transmit an RF signal related to a digital signal carried by the process control loop.

45. The apparatus of claim 30 including a HART®

module coupled to the RF communication circuitry configured to operate as a bi-directional HART®

to RF gateway unit.

46. The apparatus of claim 30 wherein the RF communication circuitry is configured for periodic communication.

47. The apparatus of claim 30 wherein the RF communication circuitry is configured to transmit an RF signal related to a process variable.

48. The apparatus of claim 30 including a connection configured to couple to a field device which couples to the two-wire process control loop.

49. The apparatus of claim 48 wherein the field device comprises a process variable transmitter configured to measure a process variable.

50. The apparatus of claim 48 wherein the radio frequency communication circuitry, the power supply circuitry and the capacitor are configured to mount in a housing of the field device.

51. A method for communicating in a field device for use in an industrial process control or monitoring system, comprising:

connecting to a two-wire process control loop configured to carry data and to provide power;

communicating using a radio frequency (RF) signal;

powering the RF communicating and storing an electrical charge in a capacitor using power received from the two-wire process control loop, and using power stored by the capacitor to power the RF communicating; and

wherein the communicating comprises bi-directional communicating.

52. The method of claim 51 wherein the communicating comprises transmitting RF data as a function of information received from the two-wire process control loop in accordance with the HART®

protocol.

53. The method of claim 51 wherein the communicating comprises digital communicating.

54. The method of claim 51 wherein the communicating comprises analog communicating.

55. The method of claim 51 wherein the connecting comprises connecting in series with the two-wire process control loop.

56. The method of claim 51 wherein the communicating includes bi-directional communication between the two wire loop and the RF signal.