HART Channel Interface Redundancy with Suicide Relay Switch
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Solution Overview
Problem
HART channel faults interrupt communication between HART devices and control systems, causing delays in control and monitoring operations.
Innovation Solution
A HART channel interface component with a suicide relay switch and programmable channel control logic that allows for redundancy by switching between master and slave channels, ensuring uninterrupted communication by disconnecting faulty channels and reconnecting redundant ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single HART channel is used for communication, then the device complexity is reduced, but the reliability of communication is worsened due to interruptions when faults occur
Solution Approach 1:
The HART channel interface is segmented into multiple independent channels (primary and secondary) that can operate separately. Each channel has its own dedicated circuitry for current loop measurements and driving functions, allowing one channel to take over when the other fails, thus improving communication reliability without requiring complete system redesign
Solution Approach 2:
A secondary HART channel is pre-configured and stood by in readiness before any fault occurs. The channel interface component includes predetermined logic that automatically activates the secondary channel when the primary channel fails, eliminating communication interruptions without requiring manual intervention or complex real-time decision-making algorithms
2Reliability
If redundancy is implemented with multiple HART channels, then the reliability is improved, but the device complexity increases due to additional components
Solution Approach 1:
The primary and secondary HART channel interfaces are merged into a single integrated channel interface component. Both channels share common control logic and physical mounting within the same device housing, allowing redundancy to be implemented without proportionally increasing overall device complexity. The shared control architecture reduces the need for duplicate management circuitry
Solution Approach 2:
The channel interface component is designed with universal functionality that can handle both primary and secondary HART channel operations through a single unified control unit. The same control logic manages current loop measurements, driving, and fault detection for both channels, eliminating the need for separate dedicated control circuits for each channel and thereby reducing overall complexity
3Loss of time
If a HART channel fault occurs, then the communication is interrupted, but adding redundancy increases the device complexity
Solution Approach 1:
The redundant HART channel configuration ensures continuous communication by automatically switching to the secondary channel when the primary channel fails. The channel interface component maintains uninterrupted current loop measurements and driving functions through this automatic failover mechanism, eliminating communication interruptions and ensuring continuous process control and monitoring operations
Data Source
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AI summary
A channel interface component (30) including redundancy within a control system with highway addressable remote transfer (HART) channels (100, 200) is provided. In one embodiment, a circuit includes: at least two highway addressable remote transfer (HART) channels (100, 200), each HART channel (100, 200) including an input terminal (105, 205) and an output terminal (110, 210) configured to connect with a HART device (25) via a current loop; an channel interface component (30) coupled to each HART channel (100, 200) that is configured to support HART protocol signals for communications with the HART device (25), wherein the channel interface component (30) includes a suicide relay switch (35) for connecting or disconnecting each HART channel (100, 200) from the HART device (25); and a programmable logic device (80) coupled to the channel interface component (30) that is configured to perform modulation and demodulation of HART protocol signals for communications with the HART device (25).