Safety Input Device Error Diagnosis and Status Data Pairing
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Solution Overview
Problem
In safety control systems, when an error is detected in an input device, it is challenging for the safety controller to determine whether the system is stopped due to a proper emergency stop or due to a fault, leading to inefficiencies in restoring the system, as current countermeasures either set control data to OFF compulsorily or shut down communication, making it difficult to differentiate between actual and error-induced states.
Innovation Solution
An input device with an error diagnostic portion that fetches self-diagnosis results from input terminals and processes these results to differentiate between actual and error-induced states, allowing the transmission of control data and status data pairs to the safety controller, enabling the controller to determine the origin of the action status, thus facilitating appropriate safety measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If error diagnostic function is added to differentiate between proper emergency stop and fault conditions, then system restoration efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines the error diagnostic portion with the input device to create an integrated unit. The diagnostic functionality is merged into the input device itself, allowing it to perform both signal reception and self-diagnosis functions simultaneously, thereby improving system restoration efficiency without adding separate complex diagnostic equipment.
Solution Approach 2:
The input device performs self-diagnosis through the error diagnostic portion that automatically detects its own operational status. This self-service capability allows the device to identify faults in itself without requiring external diagnostic equipment, thereby improving productivity while minimizing the increase in overall system complexity.
2Reliability
If control data is set to OFF compulsorily when error is detected, then safety is improved, but ability to determine error origin deteriorates
Solution Approach 1:
The patent implements feedback by having the error diagnostic portion continuously monitor and report the operational status of the input device. This feedback mechanism provides the safety controller with real-time information about whether an OFF state is due to a proper emergency stop or a fault condition, maintaining safety while preserving error origin information.
Solution Approach 2:
The patent segments the information transmission by separating control data from status data. The control data indicates the ON/OFF state while the status data independently indicates the operational status. This segmentation allows the safety controller to receive both pieces of information simultaneously, maintaining safety responses while preserving information about the error origin.
3Reliability
If communication is shut down when error is detected, then safety is improved, but system restoration time increases
Solution Approach 1:
The patent introduces status data as an intermediary information channel between the input device and safety controller. Instead of shutting down communication entirely, the status data serves as a mediator that conveys error information while maintaining the communication channel open, allowing for faster system restoration while preserving safety through continued monitoring capability.
Data Source
AI summary
This invention provides an input device of safety unit which enables an error diagnosis result referred to in a process of input processing for generating a control data from raw input signal to be referred by a side using the control data also in a safety unit such as a safety master and safety slave. An input device contains a function of outputting status data indicating the error diagnosis result referred to when input signal is converted to control data and the control data obtained by the conversion in pair, so that when the logical value of the control data is “LOW”, whether it originates from that the raw logical value is “LOW” or that “LOW” is compulsorily set due to an error in the terminal can be determined from the logical value of the status data.