Tamper Detection Circuit With Nonvolatile Logging When Unpowered
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Solution Overview
Problem
Existing tamper detection systems in industrial products are inadequate, particularly when the products are in an unpowered state, as they fail to detect and record tampering events effectively.
Innovation Solution
A tamper detection apparatus and method that includes a tamper detection circuit with a non-volatile memory to store tamper event codes, a switch to detect the opening of the enclosure, and a processor to log events, which operates even when the industrial product is unpowered, and a system processor to handle tamper event codes upon powering up, enabling notification and disabling operations if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tamper detection switches are used, then tamper detection is possible when the system is powered on, but the system cannot detect or record tampering events when in an unpowered state
Solution Approach 1:
The patent divides the tamper detection function into two independent segments: a main processor that operates when powered, and a separate tamper detection circuit with its own non-volatile memory and backup power source that operates independently. This segmentation allows the tamper detection circuit to function autonomously during unpowered states while the main processor handles normal operations when powered.
Solution Approach 2:
The patent introduces a backup power source (battery or capacitor) as an intermediary energy supply specifically for the tamper detection circuit. This intermediary power source bridges the gap between powered and unpowered states, enabling continuous operation of the tamper detection function without requiring the main system power.
2Reliability
If the system requires power to detect tampering, then energy consumption is minimized, but tamper detection fails during unpowered states when tampering is most likely to occur
Solution Approach 1:
The patent applies partial action by providing power to only the essential tamper detection circuit rather than the entire system. The backup power source supplies just enough energy to maintain the tamper detection circuit in a functional state, using minimal energy compared to powering the complete industrial control device.
Solution Approach 2:
The patent implements local quality by creating a specialized power supply arrangement where only the tamper detection circuit receives continuous power from the backup source, while the rest of the system operates normally with standard power cycling. This localized power provision ensures detection capability without excessive overall energy consumption.
3Reliability
If tamper detection is implemented throughout the system, then comprehensive security is achieved, but the system complexity and cost increase significantly
Solution Approach 1:
The patent extracts the tamper detection function from the main system architecture and implements it as a separate, dedicated circuit with its own memory and power source. This extraction isolates the security function, allowing it to operate independently without adding complexity to the main control system while still providing comprehensive tamper detection coverage.
Solution Approach 2:
The tamper detection circuit serves multiple functions: it detects physical tampering, records events in non-volatile memory, provides alarm outputs, and maintains operation during power failures. This multi-functionality achieves comprehensive security without requiring multiple separate systems, thereby limiting the increase in overall complexity.
Data Source
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AI summary
A tamper detection apparatus includes a switch and a tamper detection circuit with a non-volatile memory in an industrial product enclosure. In response to the switch detecting a door or panel of an industrial product enclosure being open when an electronic component or system in the enclosure is unpowered, the tamper detection circuit stores a tamper event code in the non-volatile memory. After the electronic component or system is powered, a system processor obtains the tamper event code from the tamper detection circuit and refrains from operating a machine or process pending reset of the industrial product by a user.