Two-wire field-mounted process device

• US 20030181996A1
• Filed: 03/26/2003
• Published: 09/25/2003
• Est. Priority Date: 05/12/2000
• Status: Active Grant

• Current Assignee: Gary A. Lenz, Marcos Peluso, Robert J. Karschnia, Steven J. Dimarco, William R. Kirkpatrick
• Original Assignee: Gary A. Lenz, Marcos Peluso, Robert J. Karschnia, Steven J. Dimarco, William R. Kirkpatrick
• Inventors: Karschnia, Robert J., Peluso, Marcos, Lenz, Gary A., Kirkpatrick, William R., DiMarco, Steven J.
• Granted Patent: US 6,711,446 B2
• Time in Patent Office: Days
• 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 process control loop and adapted to wholly power the process device with power received from the two-wire process control loop;

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

a controller coupled to the loop communicator and power module;

a first channel operably coupled to the controller and the power module and electrically isolated from the process device, the first channel configured to couple to at least a first process interface element through a plurality of first terminals; and

a second channel operably coupled to the controller and the power module and electrically isolated from the process device, the second channel being configured to couple to at least a second process interface element through a plurality of second terminals.

2. The device of claim 1, wherein the first process interface element is a sensor, and the device further includes:

a first multiplexer coupled to the plurality of first terminals;

a first analog-to-digital converter coupled to the controller and the first multiplexer, the first converter being adapted to convert an analog signal from one of the plurality of first terminals, into a digital value and to convey the digital signal to the controller.

3. The device of claim 2, wherein the second process interface element is a sensor, and the device further includes:

a second multiplexer coupled to the plurality of second terminals;

a second analog-to-digital converter coupled to the controller and the second multiplexer, the second converter being adapted to convert an analog signal from one of the plurality of second terminals, into a digital value and to convey the digital signal to the controller.

4. The device of claim 2, wherein the second process interface element provides a digital output, and the process device further includes a second multiplexer coupled to the plurality of second terminals to receive a plurality of digital inputs and convey signals to the controller based upon at least one of the digital inputs.

5. The device of claim 2, wherein the second process interface element is an actuator, and the process device further includes a second multiplexer coupled to the controller and the second plurality of terminals to provide a plurality of digital outputs on the plurality of second terminals based upon a command signal from the controller.

6. The device of claim 1, wherein the first process interface element provides a digital output, and the process device further includes a first multiplexer coupled to the controller and the plurality of first terminals to receive a plurality of digital inputs and convey signals to the controller based upon at least one of the digital inputs.

7. The device of claim 6, wherein the second process interface element provides a digital output, and the process device further includes a second multiplexer coupled to the controller and the plurality of second terminals to receive a plurality of digital inputs and convey signals to the controller based upon at least one of the digital inputs.

8. The device of claim 6, wherein the second process interface element is an actuator, and the process device further includes a second multiplexer coupled to the controller and the plurality of second terminals to provide a plurality of digital outputs on the second plurality of terminals based upon a command signal from the controller.

9. The device of claim 1, wherein the controller is a microprocessor.

10. The device of claim 9, wherein the microprocessor is a low-power microprocessor.

11. The device of claim 9, wherein the microprocessor has a clock speed that is user selectable.

12. The device of claim 1, and further comprising memory coupled to the controller and adapted to store a user-generated control algorithm.

13. The device of claim 12, wherein the control algorithm comprises a sequence of logic conditions.

14. The device of claim 12, wherein the memory is low-power memory.

15. The device of claim 12, wherein the memory is stacked memory.

16. The device of claim 12, wherein the controller is adapted to continuously execute the control algorithm.

17. The device of claim 1, wherein the power module comprises a switching-type power supply.

18. The device of claim 1, wherein the device is housed within an explosion-proof enclosure.

19. The device of claim 1, wherein the power module, loop communicator, controller, first channel, and second channel are intrinsically safe.

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

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

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

a controller coupled to the loop communicator and power module, and adapted to provide a process variable output;

a memory module coupled to the power module and the controller, the memory module being adapted to store a user-generated control algorithm relating the at least one process variable to the process output.

an input channel operably coupled to the controller and the power module and electrically isolated from the process device, the input channel being adapted to receive at least one sensor input; and

wherein the controller computes the process variable based at least in part upon a sensor signal received through the at least one sensor input and the user-generated control algorithm.

21. The device of claim 20, wherein the device is housed within an explosion-proof enclosure.

22. The device of claim 20, wherein the power module, loop communicator, controller, memory module, and input channel are intrinsically safe.

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

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

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

a controller coupled to the loop communicator and power module, and adapted to provide a process variable output based upon at least one process variable;

a memory module coupled to the power module and the controller, the memory module being adapted to store a user-generated control algorithm relating the at least one process variable to the process variable output; and

an output channel operably coupled to the controller and the power module and electrically isolated from the process device, the output channel being adapted to provide an output based upon a command signal from the controller; and

wherein the controller provides the command signal to the output channel based upon the at least one process variable and the user-generated algorithm.

24. The device of claim 23, wherein the device is housed within an explosion-proof enclosure.

25. The device of claim 23, wherein the power module, loop communicator, controller, memory module, and output channel are intrinsically safe.

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

means for wholly powering the process device with power received from a two-wire process control loop;

means for communicating over the two-wire process control loop;

means for performing input/output; and

means for performing a user-provided control algorithm based at least in part information received from the means for performing input/output.

27. A method in a field-mountable two-wire process device for providing a process variable, the method comprising:

wholly powering the process device with a two-wire process control loop;

selectively coupling the process device to a first sensor through a first isolated channel to measure a first characteristic of the first sensor;

selectively coupling the process device to a second sensor through a second isolated channel to measure a second characteristic of the second sensor;

computing a process variable based on at least one of the first and second measured characteristics; and

providing a process variable output based on the computed process variable.

28. A method in a field-mountable two-wire process device for providing a process variable, the method comprising:

wholly powering the process device with a two-wire process control loop;

coupling the process device to at least one sensor to measure at least a first characteristic of the sensor;

computing a process variable output based on operation of an user-generated algorithm and at least the first characteristics; and

providing the process variable output.