Junction Device Error Isolation for Mixed Safety and Standard Control
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Solution Overview
Problem
Existing control systems face challenges in independently managing standard and safety controls when connected to a common junction device, as transmission errors can cause unnecessary stops in other control functions, leading to inefficiencies and potential safety hazards.
Innovation Solution
A control system with a junction device that monitors periodic communication frames for errors, allowing selective switching between disabling all signal outputs or continuing updates based on unit configurations, ensuring that only affected controls are stopped, while maintaining safety and standard control functions independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common junction device is used to connect both safety controller and standard control input/output units to the network, then device complexity is reduced and space is saved, but transmission errors can cause unnecessary stops in other control functions
Solution Approach 1:
The patent segments the control functions into safety control and standard control categories, allowing independent error handling. When a transmission error is detected, the system identifies which specific control function is affected and isolates the error to that function only, preventing propagation to other functions. This segmentation enables the junction device to maintain overall system operation while handling errors locally.
Solution Approach 2:
The patent applies local quality by implementing error-specific response mechanisms for different control functions. Instead of a uniform error response that disables all functions, the system applies localized error handling that affects only the specific function experiencing the transmission error. This allows healthy control functions to continue operating with their normal signal outputs while the affected function is appropriately disabled.
2Reliability
If transmission error causes all signal outputs to be disabled, then system safety is maintained, but productivity is reduced due to unnecessary stops
Solution Approach 1:
The patent implements local quality by applying error responses selectively to specific control functions rather than uniformly to all functions. The system identifies which control function is experiencing the transmission error and applies the disable signal only to that function's output signals. This localized approach maintains safety for the affected function while preserving productivity by allowing other healthy functions to continue operating.
Solution Approach 2:
The patent converts the potential harm of transmission errors into a beneficial selective error handling mechanism. Instead of allowing errors to cause unnecessary widespread stops, the system uses error detection to trigger selective disabling of only the affected function. This transforms what would be a productivity-reducing event into an opportunity to demonstrate robust error isolation and maintain overall system productivity.
3Reliability
If separate junction devices are used for safety control and standard control, then error isolation is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent merges the safety control and standard control functions into a single junction device, eliminating the need for separate junction devices. The junction device is designed to handle multiple control functions simultaneously with independent error detection and handling capabilities for each function. This merging reduces device complexity and space requirements while maintaining the error isolation benefits through software-based function separation and selective error response.
Data Source
AI summary
The junction device includes a first error detection means that detects a transmission error by monitoring the periodic reception of a first communication frame, and a state switching means that switches, when a transmission error is detected by the first error detection means, a state of the junction device to either a first state in which the signal output from all of the functional units connected to the junction device is disabled or a second state in which the signal output from some of the functional units connected to the junction device is continuously updated based on the configuration of each functional unit connected to the junction device.