RF adapter for field device

• US 8,160,535 B2
• Filed: 05/22/2008
• Issued: 04/17/2012
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Kielb, John A., Karschnia, Robert J., Westfield, Brian L., Orth, Kelly M., Broden, David A.
• Primary Examiner(s): Nguyen, Duc M
• Application Number:
  US12/125,187
• Publication Number:
  US 20080280568A1
• Time in Patent Office: 1,426 Days
• Field of Search: 455/572, 455/573, 455/574, 455/343.1, 455/343.2, 455/343.5, 340/539.1, 340/693.1, 340/693.4, 323/220, 323/242, 323/282, 323/288
• US Class Current: 455/343.1
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G05B 19/4185 characterised by the network communication
• CPC Class Codes: G05B 2219/31121 Fielddevice, field controller, interface connected to fieldbus
• CPC Class Codes: G05B 2219/33192 Radio link, wireless
• CPC Class Codes: G05B 2219/34313 Power supply for communication delivered by, derived from 4-20-mA current loop
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• 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

An adapter for coupling to a process control transmitter of the type used to monitor a process variable in an industrial process is provided. The adapter includes I/O circuitry configured to couple to a two wire process control loop and to the process control transmitter and communicate on the process control loop. Wireless communication circuitry couples to the two wire process control loop and is configured to transmit an RF signal. Power supply circuitry provides power to the wireless communication circuitry.

Claims

1. An adapter for coupling to a process control transmitter of the type used to monitor a process variable in an industrial process, the adapter comprising:

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

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

power supply circuitry coupled to the two wire process control loop configured to provide power to the wireless communication circuitry;

bypass circuitry connected in parallel with the power supply circuitry; and

wherein the power supply circuitry and the bypass circuitry are configured to connect in series with the two wire process control loop.

2. The apparatus of claim 1 wherein the I/O circuitry includes a digital signal connection configured to digitally communicate on the two wire process control loop.

3. The apparatus of claim 2 wherein the digital communication is in accordance with the HART®

communication protocol.

4. The apparatus of claim 2 wherein the digital signal connection is coupled in parallel with the process control transmitter.

5. The apparatus of claim 1 including level shifting circuitry configured to communicate with the wireless communication circuitry.

6. The apparatus of claim 1 including a plurality of voltage regulators arranged to power circuitry of the adapter with power received from the two wire process control loop.

7. The apparatus of claim 1 wherein the bypass circuitry includes an OP amp arranged to maintain a desired voltage level across loop connections of the adapter configured to couple to the two wire process control loop.

8. The apparatus of claim 7 wherein the voltage across the loop terminals is adjustable.

9. The apparatus of claim 1 including a capacitor coupled in series with a transistor of the bypass circuitry configured to store charge from the two wire process control loop.

10. The apparatus of claim 9 including circuitry arranged to monitor a voltage of the capacitor.

11. The apparatus of claim 9 including a step up converter coupled to the capacitor configured to provide an output voltage which is greater than a voltage stored on the capacitor.

12. The apparatus of claim 11 including a linear voltage regulator coupled to the output of the step up voltage regulator, the linear voltage regulator arranged to provide power to the RF communication circuitry.

13. The apparatus of claim 1 including a step up converter coupled to loop terminals of the adapter, the step up converter configured to provide an output voltage which is greater than a voltage across the loop terminals.

14. The apparatus of claim 13 including a linear voltage regulator coupled to the output of the step up regulator, the linear voltage regulator arranged to provide power to circuitry of the adapter.

15. The apparatus of claim 1 including a microcontroller arranged to control operation of the wireless communication circuitry.

16. The apparatus of claim 15 including level shifting circuitry arranged to couple the microcontroller to the wireless communication circuitry.

17. The apparatus of claim 15 including reset circuitry arranged to reset the microcontroller.

18. The apparatus of claim 1 wherein the microcontroller controls operation of the I/O circuitry.

19. The apparatus of claim 18 wherein the microcontroller operates as a modulator/demodulator (modem) in controlling operation of the I/O circuitry.

20. The apparatus of claim 1 including a capacitor coupled in series with the bypass circuitry arranged to store power from the two wire process control loop and a voltage clamp coupled in parallel with the capacitor, the voltage clamp arranged to shunt loop current when a voltage across the voltage clamp and capacitor is greater than voltage clamp level.

21. The apparatus of claim 1 including a housing configured to mount to the process control transmitter.

22. The apparatus of claim 21 wherein the housing includes a RF transmissive region which allows the RF signal to pass therethrough.

23. The apparatus of claim 1 wherein the housing is threadably received in a threaded coupling of the process control transmitter.

24. A method of providing wireless communication capabilities to an existing process control transmitter of the type used to monitor a process variable in an industrial process, the method comprising:

electrically coupling to the process control transmitter and to a two wire process control loop and communicating on the two wire process control loop;

transmitting an RF signal based upon data carried on the two wire process control loop;

providing power to the wireless communication circuitry with power received from the two wire process control loop, wherein the power supply circuitry is coupled in series with the two wire process control loop; and

selectively bypassing a loop current of the two wire process control loop around the power supply circuitry.

25. The method of claim 24 including providing a digital signal connection configured to digitally communicate on the two wire process control loop.

26. The method of claim 25 wherein the digital communication is in accordance with the HART®

communication protocol.

27. The method of claim 25 wherein the digital signal connection is coupled in parallel with the process control transmitter.

28. The method of claim 24 including level shifting a signal to communicate with wireless communication circuitry.

29. The method of claim 24 including providing a plurality of voltage regulators arranged to power circuitry with power received from the two wire process control loop.

30. The method of claim 24 wherein selectively bypassing includes setting a desired voltage level across loop connections couples to the two wire process control loop.

31. The method of claim 30 wherein the voltage across the loop terminals is adjustable.

32. The method of claim 24 including providing a capacitor coupled in series with a transistor of the bypass circuitry configured to store charge from the two wire process control loop.

33. The method of claim 32 including monitoring a voltage of the capacitor.

34. The method of claim 32 including step up generating an output voltage which is greater than a voltage stored on the capacitor.

35. The method of claim 24 including generating an output voltage which is greater than a voltage across loop terminals.

36. The method of claim 24 including providing a microcontroller operating as a modulator/demodulator (modem) in controlling operation of I/O circuitry.

37. The method of claim 24 including providing a capacitor coupled in series with bypass circuitry arranged to store power from the two wire process control loop and a voltage clamp coupled in parallel with the capacitor, the voltage clamp arranged to shunt loop current when a voltage across the voltage clamp and capacitor is greater than voltage clamp level.

38. The method of claim 24 including coupling an adapter to a housing of the process control transmitter.