Two-wire field-mounted process device

• US 6,961,624 B2
• Filed: 01/20/2004
• Issued: 11/01/2005
• Est. Priority Date: 05/12/2000
• Status: Expired due to Term

• Current Assignee: Ecopia BioSciences, Inc. (Sun Pharmaceutical Industries Limited)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Karschnia, Robert J., Peluso, Marcos, Lenz, Gary A., Kirkpatrick, William R., DiMarco, Steven J.
• Primary Examiner(s): PATEL, RAMESH B
• Application Number:
  US10/760,793
• Publication Number:
  US 20040158334A1
• Time in Patent Office: 651 Days
• Field of Search: 700 1- 3, 700 27- 30, 700/9, 700/11, 700/17, 700/37, 700/83, 700/79, 710/11, 710/12, 710/16, 710/105, 710/38, 714/6, 714/11, 370/410, 370/437, 370/493, 370/468
• US Class Current: 700/19
• CPC Class Codes: G05B 19/054 Input/output
• CPC Class Codes: G05B 2219/1127 Selector for I-O, multiplex for I-O
• CPC Class Codes: G05B 2219/1157 I-O used either as input or as output
• CPC Class Codes: G05B 2219/1163 Multiplexer for analog signals
• CPC Class Codes: G05B 2219/14144 Galvanic isolation
• CPC Class Codes: G05B 2219/15091 Power and data bus
• CPC Class Codes: G05B 2219/25188 Superposition high frequency data signal on power lines, current carrier
• CPC Class Codes: G06F 1/182 with special features, e.g. for use in industrial environments; grounding or shielding against radio frequency interference [RFI] or electromagnetical interference [EMI]
• CPC Class Codes: G06F 3/05 Digital input using the sampling of an analogue quantity at regular intervals of time , input from a/d converter or output to d/a converter
• CPC Class Codes: H05K 7/1472 Bus coupling modules, e.g. bus distribution modules
• CPC Class Codes: H05K 7/1484 Electrical diagrams relating to constructional features, e.g. signal routing within PLC; Provisions for disaster recovery, e.g. redundant systems

Abstract

A two-wire field-mounted process device with multiple isolated channels includes a channel that can be an input channel or an output channel. The given input or output channel can couple to multiple sensors or actuators, respectively. The process device is wholly powered by the two-wire process control loop. The process device includes a controller adapted to measure one or more characteristics of sensors coupled to an input channel and to control actuators coupled to an output channel. The controller can be further adapted to execute a user generated control algorithm relating process input information with process output commands. The process device also includes a loop communicator that is adapted to communicate over the two-wire loop.

Claims

1. A two-wire field-mountable process device comprising:

a power module couplable to a two-wire loop and adapted to wholly power the process device with power received from the two-wire loop;

a loop communicator coupled to the power module, and being couplable to the two-wire loop to communicate on the two-wire loop in accordance with the Fieldbus or Profibus protocol, wherein the communicator is configured to provide an output on the loop;

a controller coupled to the loop communicator and power module;

a first channel operably coupled to the controller, the first channel configured to couple to at least a first sensor and configured to receive a sensor input;

a second channel operably coupled to the controller, the second channel configured to couple to a second sensor and receive a sensor input; and

wherein the first and second channels are substantially electrically isolated from each other and from the two-wire loop.

2. The process device of claim 1 wherein the first sensor is of a first type, the second sensor is of a second type, and wherein the first and second types are different.

4. The process device of claim 1 and further comprising:

a first analog-to-digital converter operably coupled to the first channel and to the controller, the first converter being adapted to convert an analog signal from the first channel, into at least one digital value at a first conversion rate, and to convey the digital signal to the controller; and

a second analog-to-digital converter operably coupled to the second channel and to the controller, the second converter being adapted to convert an analog signal from the second channel, into at least one digital value at a second conversion rate, and to convey the digital signal to the controller; and

wherein the first and second conversion rates are different.

5. The process device of claim 4 wherein the first conversion rate is related to a type of sensor to be coupled to the first sensor terminals.

6. The process device of claim 5 wherein the second conversion rate is related to a type of sensor to be coupled to the second sensor terminals.

7. The process device of claim 1 and further comprising:

a multiplexer coupled to the first channel; and

an analog-to-digital converter operably coupled to the first channel via the multiplexer, the analog-to-digital converter being operably coupled to the controller, wherein the analog-to-digital converter is adapted to convert an analog signal from the first sensor terminals, into at least one digital value and to convey the digital signal to the controller.

8. The process device of claim 1 wherein the controller operates in accordance with a program.

9. The process device of claim 8 wherein the program can be changed.

10. The process device of claim 9 wherein the program can be changed by accessing the device through the two-wire loop.

11. The process device of claim 8 wherein the program relates an input to the output.

12. The process device of claim 1 wherein the controller computes a process variable based upon a sensor input.

13. The process device of claim 1 wherein the process device is in accordance with a DIN standard.

14. The process device of claim 1 wherein the process device complies with an intrinsic safety specification.

15. The process device of claim 1 including third sensor input operably coupled to the controller, the third sensor input configured to couple to a third sensor and configured to receive a third sensor input.

16. The process device of claim 15 including a multiplexer configured to selectively couple the sensors to the controller.

17. The process device of claim 16 including an analog to digital converter coupled to an output of the multiplexer and to the controller configured to provide a digitized signal to the controller.

18. The process device of claim 1 wherein the loop communicator includes isolation circuitry.

19. The process device of claim 1 including a power module which is configured to power circuitry of the first and second channels.

3. The process device 2 wherein the first type is selected from the group of sensors consisting of thermocouples and RTDs.

20. A two-wire field-mountable process device comprising:

a power module couplable to a two-wire loop and adapted to wholly power the process device with power received from the two-wire loop;

a loop communicator coupled to the power module, and being couplable to the two-wire loop to communicate on the two-wire loop;

a controller;

first sensor terminals configured to couple to at least a first sensor and configured to receive a sensor characteristic;

second sensor terminals configured to couple to a second sensor and configured to receive a sensor characteristic the second sensor terminals operably coupled to the controller;

third sensor terminals configured to couple to a third sensor and configured to receive a third sensor characteristic;

a multiplexer configured to selectively couple the first sensor terminals to the controller or the third sensor terminals to the controller;

an analog to digital converter coupled to an output of the multiplexer and to an input of the controller, the analog to digital converter configured to provide a digitized signal to the controller;

wherein an output from the loop communicator on the two-wire process control loop is related to at least one of the first, second or third sensor characteristics; and

wherein at least the first and second sensor terminals are substantially electrically isolated from each other and from the two-wire loop and the second and third sensor terminals are substantially electrically isolated from each other and from the two wire loop.

21. The process device of claim 20 wherein the first sensor is of a first type, the second sensor is of a second type, and wherein the first and second types are different.

22. The process device of claim 20 wherein the first sensor is selected from the group of sensors consisting of thermocouples and RTDs.

23. The process device of claim 20 comprising:

a second analog-to-digital converter operably coupled to the second sensor terminals and to the controller.

24. The process device of claim 20 wherein the controller operates in accordance with a program.

25. The process device of claim 24 wherein the program can be changed.

26. The process device of claim 25 wherein the program can be changed by accessing the device through the two-wire loop.

27. The process device of claim 24 wherein the program relates a sensor characteristic to the output.

28. The process device of claim 24 wherein the controller computes a process variable based upon a sensor characteristic.

29. The process device of claim 20 wherein the process device is in accordance with a DIN standard.

30. The process device of claim 20 wherein the process device complies with an intrinsic safety specification.

31. The process device of claim 20 wherein the loop communicator includes isolation circuitry.

32. The process device of claim 20 including a power module which is configured to power circuitry of the first sensor terminals, circuitry of the second sensor terminals, and circuitry of the third sensor terminals.

33. The process device of claim 20 wherein including a first channel which includes the first and third sensor terminals.

34. The process device of claim 33 including a second channel which includes the second sensor terminals.

35. A two-wire field-mountable process device comprising:

a power module couplable to a two-wire loop and adapted to wholly power the process device with power received from the two-wire loop;

a loop communicator coupled to the power module, and being couplable to the two-wire loop to communicate on the two-wire loop;

a controller coupled to the loop communicator and power module;

a first channel operably coupled to the controller, the first channel configured to couple to at least a first sensor;

a second channel operably coupled to the controller, the second channel configured to couple to a second sensor;

wherein the first and second sensor channels are substantially electrically isolated from each other; and

wherein circuitry of the first channel and circuitry of the second channel are powered by the power module.

36. The process device of claim 35 including a connection to a third sensor.

37. The process device of claim 36 including a multiplexer configured to selectively couple the first sensor to the controller or the third sensor to the controller.

38. The process device of claim 37 including an analog to digital converter coupled to an output of the multiplexer and to the controller configured to provide a digitized signal to the controller.

39. The process device of claim 36 wherein the power module is configured to power circuitry of the connection to the sensor.

40. The process device of claim 35 wherein the power module simultaneously powers the circuitry of the first channel and circuitry of the second channel.