Bandwidth-Efficient Serial Protocol for Safety-Critical Medical Systems
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Solution Overview
Problem
Current communications protocols in safety critical medical systems, such as surgical equipment, suffer from excessive overhead, high bandwidth requirements, limited error detection, and lack of system integrity, which can lead to unsafe system behavior and potential harm to patients due to inadequate error correction and lack of a reliable communications watchdog mechanism.
Innovation Solution
A bandwidth-efficient communications protocol that employs a master-slave relationship between software modules, using data packets with a start indication, message identifier, service identifier, arbitrary length of data, checksum, and checksum complement, along with a safety critical communications watchdog to monitor and ensure data integrity and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standardized communications protocols (XModem, ZModem, Kermit, MNP, CCITT V.42) are used for transmitting control and status signals between subsystems, then data transmission capability is provided, but excessive overhead and high bandwidth requirements increase system complexity and processing resource requirements
Solution Approach 1:
The patent changes the parameters of the communication protocol by implementing a custom protocol with modified data packet structure (including start indication, message identifier, service identifier, arbitrary length data, checksum, and checksum complement) and altered transmission parameters (9600 baud, 8 data bits, no parity, 1 stop bit) to reduce overhead while maintaining reliability
Solution Approach 2:
The patent segments the data transmission into structured data packets with specific fields (start indication, message identifier, service identifier, data portion, checksum, checksum complement) to enable efficient processing and reduced overhead compared to traditional protocols
2Ease of operation
If traditional cable interfaces (USB, Ethernet) with standardized protocols are used for subsystem communication, then communication capability is achieved, but lack of communications watchdog mechanism compromises system integrity in safety critical applications
Solution Approach 1:
The patent implements preliminary error detection measures by incorporating checksum and checksum complement fields in each data packet before transmission, enabling the receiving module to detect transmission errors and request retransmission, thus preventing unsafe operations
Solution Approach 2:
The patent implements a feedback mechanism where the receiving module sends acknowledgment packets (ACK or NACK) based on checksum verification results, and the transmitting module retransmits data if errors are detected, ensuring reliable communication in safety critical systems
3Loss of information
If existing protocols are used for inter-module communication, then basic data exchange is enabled, but excessive processing resources (CPU cycles, memory) are required to execute the protocol
Solution Approach 1:
The patent extracts only the essential elements needed for reliable communication (start indication, message identifier, service identifier, data, checksum, checksum complement) and removes unnecessary protocol overhead, thereby reducing processing resource requirements while maintaining data exchange capability
Data Source
AI summary
A method and system of establishing communications between at least two independent software modules in a safety critical system, such as a medical system, 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 an arbitrary length of data between the master and slave modules, wherein the arbitrary length of 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 safety critical communications watchdog between the master and slave modules, wherein the safety critical communications watchdog monitors communications quality between the master and slave modules. The protocol comprises bytes transmitted using a packet consisting of a start indication, a message identifier, an optional service identifier, a class identifier, an arbitrary length of data pertinent to the medical device comprising optional data, a checksum, and a checksum complement.