Fail-Safe Network Control via Diagnostic Signal Feedback
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Solution Overview
Problem
Existing network-capable control systems require expensive and complex 'safe' input modules for fail-safe operation, which is not feasible with conventional, non-safe input modules.
Innovation Solution
Implementing a method that uses a conventional input module connected to a controller via a communication network, where diagnostic signals are transmitted to an output module, processed, and converted back to sensor-compliant signals for error detection, allowing the controller to identify errors within the input module, output module, or communication network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If safe input modules with integrated diagnostic measures are used, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The invention introduces an intermediary diagnostic system where the controller generates test signals that travel through the output module, communication network, and input module back to the controller. This intermediary test signal path enables diagnostic capability without requiring complex safe input modules, as the controller acts as the central diagnostic coordinator using existing system components.
Solution Approach 2:
The controller is designed to perform multiple functions: normal control operations and diagnostic signal generation/evaluation. By making the controller universal, the system eliminates the need for specialized safe input modules, as the controller can both control the output module and diagnose the input module through the same communication network infrastructure.
2Reliability
If safe input modules with integrated diagnostic measures are used, then reliability is improved, but cost increases
Solution Approach 1:
The system performs self-diagnosis using its own existing components. The controller generates test signals that traverse through the output module, communication network, and input module, then evaluates the returned signals to detect faults. This self-service approach eliminates the need for expensive external diagnostic equipment or specialized safe input modules, reducing overall system cost while maintaining reliability.
Solution Approach 2:
The communication network acts as an intermediary carrier for both normal data transmission and diagnostic test signals. By utilizing the existing communication infrastructure for dual purposes, the system avoids additional expensive diagnostic hardware, making fail-safe operation cost-effective.
3Device complexity
If conventional input modules are used without integrated diagnostics, then device complexity is reduced, but reliability deteriorates
Solution Approach 1:
The diagnostic system implements feedback by sending test signals from the controller through the output module and input module, then evaluating the returned signals at the controller. This feedback loop enables error detection in conventional input modules without adding complexity to the input module itself, maintaining simplicity while achieving reliability through system-level diagnostics.
Solution Approach 2:
The controller performs preliminary diagnostic actions by generating test signals before normal operation to detect potential faults. This preliminary testing capability allows conventional input modules to be diagnosed proactively, compensating for their lack of integrated diagnostics while maintaining their simplicity.
Data Source
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AI summary
The invention relates to a method for the fail-safe operation of a network-enabled control system, wherein the control system comprises: - at least one controller (1), - at least one input assembly (30) having two or more signal inputs (30A), - at least one sensor (S, S1) connected to the input assembly (30) and connected to a first signal input (30A) of the input assembly (30), - wherein the input assembly (30) is connected to the controller (1) via a communication network (2), - wherein the input assembly (30) serves to process and/or convert the sensor signals for data transmission via the communication network (2) to the controller (1), and - wherein the at least one signal output (4A) of an output assembly (4) is connected to a second signal input (3A) of the input assembly (30).- the output module (4) is configured to process and/or convert the diagnostic signals received via the communication network (2) into sensor-signal-compliant signals for output via the signal output (4A) to the second signal input (30A) of the input module (30), - the signals generated by the output module (4) based on the diagnostic signals and output to the input module (30) are transmitted back to the controller (1) by the input module (30) in a further processed form via the communication network (2), - the controller (1) is configured to detect faults within the input module (30), the output module (4) and/or the communication network (2) by evaluating the transmitted diagnostic signals and the signals subsequently transmitted back by the input module (30).