Bandwidth-Efficient Serial Protocol With Watchdog For Safety-Critical Systems
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Solution Overview
Problem
Current communications protocols in safety-critical systems face issues with excessive overhead, high bandwidth requirements, limited error detection and correction, and the lack of a reliable watchdog mechanism, which can lead to system failures and safety risks.
Innovation Solution
A bandwidth-efficient communications protocol that employs a master-slave relationship between software modules, using data packets with a checksum and a communications watchdog to ensure data integrity and monitor communication quality, impairing functionality when quality degrades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standardized communications protocols (XModem, ZModem, Kermit, MNP, CCITT V.42) are used for module communication, then data transmission capability is provided, but excessive overhead and bandwidth requirements increase system complexity and cost
Solution Approach 1:
The patent extracts only the essential error detection functionality (checksum) from complex standardized protocols, implementing a custom lightweight protocol that provides reliable communication without the excessive overhead of protocols like XModem or ZModem. The custom protocol includes only necessary elements: start marker, command byte, data bytes, and checksum, eliminating unnecessary protocol complexity while maintaining communication reliability.
Solution Approach 2:
The patent changes the protocol parameters by defining a custom message structure with specific byte formats (start marker 0x02, command bytes, data bytes, checksum calculation) that optimizes for low overhead. This parameter customization allows the system to achieve reliable communication with minimal bandwidth consumption and processing requirements, directly addressing the contradiction between reliability and complexity.
2Ease of manufacture
If existing protocols are used without modification, then implementation simplicity is maintained, but lack of watchdog mechanism compromises system integrity in safety-critical applications
Solution Approach 1:
The patent merges the communication protocol with a watchdog mechanism into a unified system. The same communication infrastructure transmits both data commands and watchdog timing information. The master module sends periodic watchdog commands, and the slave module uses received commands to reset its watchdog timer, combining communication and safety monitoring functions into a single integrated approach that maintains implementation simplicity while ensuring system integrity.
Solution Approach 2:
The patent implements feedback through the watchdog mechanism where the master module continuously monitors communication health by sending periodic commands and the slave module responds by resetting its watchdog timer. This feedback loop provides real-time monitoring of communication quality and system integrity without adding separate complex monitoring infrastructure, maintaining ease of implementation while enhancing reliability.
3Reliability
If comprehensive error detection and correction are implemented, then data integrity is improved, but processing resource requirements increase
Solution Approach 1:
The patent applies partial error detection by implementing only a checksum mechanism rather than full error detection and correction. The checksum provides sufficient data integrity for the application by detecting transmission errors, while avoiding the excessive processing resources required by comprehensive error correction codes. This partial approach balances data integrity requirements with processing efficiency, using only the necessary level of error protection.
Data Source
AI summary
A method and system of establishing communications between at least two independent software modules is provided. The design comprises providing a media connection between software modules, wherein the software modules employ a communications protocol and participate in a bi-directional master-slave relationship between a master module and a slave module. The design further comprises sending arbitrary data between the master and slave modules, wherein the arbitrary data is used by the master module to control and obtain status from the slave module, and sending arbitrary data further enables the slave module to return data and status information to the master module. The design also employs a communications watchdog between the master and slave modules, wherein the communications watchdog monitors communications quality between the master and slave modules and impairs functionality in the master and slave modules when communications quality degrades. The bandwidth efficient communications protocol comprises bytes transmitted using a packet consisting of a start indication, a message identifier, an optional service identifier, a class identifier, an optional length of data pertinent to the medical device, a checksum, and a checksum complement.