Two-wire field-mounted process device

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.

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 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 input connection operably coupled to the controller, the first input connection configured to couple to at least a first sensor and configured to receive a sensor input; and    a second input connection operably coupled to the controller, the second input connection configured to couple to a second sensor and receive a sensor input; and    wherein the first and second input connections are substantially electrically isolated from each other and from the two-wire loop.    
   
   
       2 - 28 . (canceled)  
   
   
       29 . 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.  
   
   
       30 . The process device of  claim 29  wherein the first type is thermocouples.  
   
   
       31 . The process device of  claim 29  wherein the first type is RTDs.  
   
   
       32 . The process device of  claim 1  and further comprising: 
 a first analog-to-digital converter operably coupled to the first input connection and to the controller, the first converter being adapted to convert an analog signal from the at least one first sensor input, into at least one digital value at a fist conversion rate, and to convey the digital signal to the controller; and    a second analog-to-digital converter operably coupled to the second input connection and to the controller, the second converter being adapted to convert an analog signal from the at least one second sensor input, 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.    
   
   
       33 . The process device of  claim 32  wherein the first conversion rate is related to a type of sensor to be coupled to the first input connection.  
   
   
       34 . The process device of  claim 33  wherein the second conversion rate is related to a type of sensor to be coupled to the second input connection.  
   
   
       35 . The process device of  claim 1  wherein at least one of the sensors is a temperature sensor.  
   
   
       36 . The process device of  claim 1  and further comprising: 
 a multiplexer coupled to the first input connection; and    an analog-to-digital converter operably coupled to the first input connection 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 at least one first sensor input, into at least one digital value and to convey the digital signal to the controller.    
   
   
       37 . The process device of  claim 1  wherein the controller operates in accordance with a program.  
   
   
       38 . The process device of  claim 37  wherein the program can be changed.  
   
   
       39 . The process device of  claim 38  wherein the program can be changed by accessing the device or the two-wire loop.  
   
   
       40 . The process device of  claim 37  wherein the program relates on input to the output.  
   
   
       41 . The process device of  claim 39  wherein the controller computes a process variable based upon a sensor input.  
   
   
       42 . The process device of  claim 1  wherein the process device is in accordance with a DIN standard.  
   
   
       43 . The process device of  claim 1  wherein the process device complies with an intrinsic safety specification.  
   
   
       44 . The process device of  claim 1  including a third input connection operably coupled to the controller, the third input connection configured to couple to a third sensor and configured to receive a third sensor input.  
   
   
       45 . The process device of  claim 44  including a multiplexer configured to selectively couple the first input to the controller or the third input to the controller.  
   
   
       46 . The process device of  claim 45  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.  
   
   
       47 . The process device of  claim 1  wherein the loop communicator includes isolation circuitry.  
   
   
       48 . The process device of  claim 1  including a power module which is configured to power circuitry of the first input connection and circuitry of the second input connection.  
   
   
       49 . 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 a digital protocol, wherein the communicator is configured to provide an output of the loop;    a controller coupled to the loop communicator and power module;    a first input connection operably coupled to the controller, the first input connection configured to couple to at least a first sensor and configured to receive a sensor input;    a second input connection operably coupled to the controller, the second input connection configured to couple to a second sensor and receive a sensor input; and    wherein the first and second input connections are substantially electrically isolated from each other and from the two-wire loop.    
   
   
       50 . The process device of  claim 49  wherein the digital protocol comprises the Fieldbus protocol.  
   
   
       51 . The process device of  claim 49  wherein the digital protocol comprises the Profibus protocol.  
   
   
       52 . The process device of  claim 49  including a power module which is configured to power circuitry of the first input connection and circuitry of the second input connection.  
   
   
       53 . 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 input connection operably coupled to the controller, the first input connection configured to couple to at least a first sensor and configured to receive a sensor input;    a second input connection operably coupled to the controller, the second input connection configured to couple to a second sensor and receive a sensor input;    wherein the first and second input connections are substantially electrically isolated from each other; and    wherein circuitry of the first input connection and circuitry of the second input connection are powered by the power module.    
   
   
       54 . The process device of  claim 53  including a third input connection operably coupled to the controller, the third input connection configured to couple to a third sensor and configured to receive a third sensor input.  
   
   
       55 . The process device of  claim 54  including a multiplexer configured to selectively couple the first input to the controller or the third input to the controller.  
   
   
       56 . The process device of  claim 55  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.  
   
   
       57 . The process device of  claim 54  wherein the power module is configured to power circuitry of the third input connection.