Field Control Device Pre-defined Error-State Controller
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Solution Overview
Problem
Field control devices often fail to maintain accuracy and reliability when communication between the controller and control system is interrupted, leading to inaccurate valve positioning and potential process failures.
Innovation Solution
A field control device equipped with a local control system that employs pre-defined error-state instructions to manage the device's operation when an error condition is detected, allowing it to maintain a predetermined position or condition even without communication from the control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the field control device relies on continuous communication from the remote control system, then the valve positioning accuracy is maintained during normal operation, but the device fails to maintain reliability when communication is interrupted
Solution Approach 1:
The controller is pre-configured with error-state instructions that define predetermined positions or conditions for various error scenarios. When communication is interrupted, the controller automatically executes these pre-planned instructions without requiring real-time communication with the remote control system, thus maintaining reliability during communication failures
Solution Approach 2:
The field control device incorporates a self-diagnostic capability that allows the controller to detect communication errors and autonomously transition to error-state operation. The device serves itself by monitoring its own communication status and automatically implementing corrective actions based on stored error-state instructions, reducing dependency on external control systems
2Ease of operation
If the field control device maintains continuous communication with the control system, then real-time control is achieved, but the device cannot operate independently during communication failures
Solution Approach 1:
The controller stores multiple error-state instructions in memory, each defining a predetermined position or condition for specific error scenarios. These instructions are prepared in advance and automatically executed when communication is lost, enabling the device to operate independently without real-time control signals
Solution Approach 2:
The error-state instructions act as an intermediary between the loss of control signals and the valve position. Instead of directly responding to communication failures, the controller uses pre-defined instructions as a mediator to determine the appropriate valve position, maintaining operational continuity during signal loss
3Reliability
If the controller remains in its last position during communication errors, then simple operation is maintained, but process stability and safety are compromised
Solution Approach 1:
The controller is pre-configured with error-state instructions that specify predetermined positions for various error conditions. Instead of simply maintaining the last position, the controller executes these pre-planned instructions to transition the valve to a safe or appropriate position, thereby maintaining process stability during communication failures
Solution Approach 2:
The controller continuously monitors communication status and provides feedback about error conditions. When communication is lost, the controller detects the error state and automatically executes corresponding error-state instructions, creating a feedback loop that maintains process stability by responding appropriately to communication failures
Data Source
AI summary
Control apparatus having pre-defined error-states and related methods are described. An example non-transitory computer-readable medium disclosed herein comprises instructions that, when executed, cause a machine to analyze, via a controller coupled to a field device, a communication from a control system remotely located from the controller, the control system to operate the field control device during a non-error condition; detect an error condition while the field control device is communicatively coupled to and receives the communication from the control system; and override the communication between the control system and the controller to operate the field control device based on a pre-defined error-state instruction stored in the controller when the error condition is detected to cause the field control device to move to a first position for a first amount of time and subsequently move the field control device to a second position for a second amount of time, the first position being different than the second position.