USB Plug-in Module for Fail-Safe Time Signal Generation
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Solution Overview
Problem
Standard PCs with software PLCs face hardware dependency and limitations in meeting safety requirements for safety-critical systems, such as those in industrial processes, due to their reliance on system clocks that may not adequately detect non-critical failures, restricting their use in safety-critical applications.
Innovation Solution
A device with an independent time base generator, utilizing a microcontroller and a security module, provides a fail-safe time signal and encryption, allowing standard PCs to be used in safety-critical processes by plugging in a compact module that includes a USB connection, license key management, and software for a programmable logic controller, ensuring compliance with safety standards and protecting know-how.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard PC with software PLC is used, then hardware flexibility and ease of operation are improved, but reliability and error detection capability deteriorate due to hardware dependency and insufficient independent time base
Solution Approach 1:
A USB interface device serves as an intermediary between the standard PC and the safety-critical software PLC, providing the necessary independent time base through its internal oscillator. This mediator enables standard PCs to meet safety requirements without requiring specialized hardware while maintaining reliability through the independent time signal generated by the USB device's crystal oscillator.
2Reliability
If an independent time base is added to a computing system, then reliability and error detection capability are improved, but device complexity increases
Solution Approach 1:
The USB interface device performs multiple functions: it provides the independent time base required for safety-critical operations, serves as a communication interface between the PC and external devices, and can function as a general-purpose USB controller. This multi-functionality allows a single device to meet safety requirements without adding separate dedicated time base hardware, thereby reducing overall system complexity.
Data Source
Figure 1~3
AI summary
To upgrade a standard PC system to a fail-safe computing system (30), it is proposed to provide a device (1) with a plug-in means (2) for plugging into the computing system (30), a memory module (3), a microcontroller (5) and a first means (11) for generating a first time signal, wherein the microcontroller (5) and the first means cooperate to provide the first time signal to the computing system (30) via the plug-in means (2).