Transmitter Current Controller Segmentation for Reliability
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Solution Overview
Problem
Current transmitters lack sufficient reliability and safety integrity levels, particularly in safety instrumented systems, where failures can compromise the accuracy and continuity of current signals, leading to potential safety hazards and increased processor load.
Innovation Solution
A transmitter design that incorporates a current controller capable of detecting failures and anomalies, allowing continuous output of current signals regardless of processor state, with error detection and correction mechanisms, and the ability to select between internal and external data sources, thereby enhancing reliability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processor handles all control functions including current output control and failure detection, then the processor can execute complex processing tasks, but the processor load increases and reliability decreases when processor failures occur
Solution Approach 1:
The transmitter control functions are segmented into two independent parts: the processor handles high-level control and communication, while the current controller handles real-time current output control and failure detection. This segmentation allows each component to specialize in specific tasks, reducing the processor load while maintaining system reliability through independent failure detection capabilities.
Solution Approach 2:
The current controller acts as an intermediary between the processor and the current output interface. It receives control signals from the processor, monitors the actual current output, and independently detects failures by comparing expected versus actual values. This intermediary role protects the system from processor failures and reduces the processing burden on the main processor.
2Measurement precision
If the processor continuously monitors current output for failure detection, then failure detection accuracy improves, but the processor load increases and may obstruct general-purpose processing
Solution Approach 1:
The failure detection function is extracted from the processor and implemented in the current controller. The current controller continuously monitors the current output and compares it with expected values, independently detecting failures without involving the processor. This extraction maintains high measurement precision for failure detection while freeing the processor for general-purpose processing tasks.
Solution Approach 2:
The current controller performs self-monitoring and self-diagnosis of the current output interface. It autonomously detects failures by comparing its own output commands with the actual current measurements, without requiring external monitoring from the processor. This self-service approach ensures continuous failure detection while minimizing processor involvement.
3Reliability
If the transmitter uses a high-specification processor to handle all control and monitoring functions, then processing capability and reliability are improved, but the system cost increases
Solution Approach 1:
The system architecture is segmented to separate critical real-time functions from general processing functions. The current controller, using simpler and less expensive hardware, handles time-critical current control and failure detection. The processor, which can be lower specification, handles non-critical tasks such as communication and user interface management. This segmentation reduces overall system cost while maintaining reliability through dedicated real-time monitoring.
Solution Approach 2:
Different parts of the system are assigned different levels of processing capability according to their specific needs. The current controller requires only basic processing for real-time current control and simple comparison-based failure detection, while the processor provides higher-level intelligence for communication and configuration. This local quality approach avoids over-provisioning expensive processing power in areas where it is not needed, reducing overall system cost.
Data Source
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AI summary
A transmitter (1) includes a processor (10) that connects to a sensor (3) for outputting measurement data and outputs setting data based on the measurement data, a current controller (20) that outputs output data based on the setting data from the processor (10), a current output interface (30) that outputs a first current signal based on the output data from the current controller (20), and a current input interface (40) that receives input of a second current signal and outputs input data based on the second current signal to the current controller (20). The current input interface (40) outputs internal input data based on the first current signal to the current controller (20) as the input data when receiving input of the first current signal as the second current signal. The current controller (20) detects failure of the transmitter (1) by comparing the setting data and the internal input data.