Ethernet Safety Packet CRC Using Virtual Sequence Numbers
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Solution Overview
Problem
Industrial control systems face challenges in maintaining data integrity due to issues like corruption, unintended repetition, incorrect sequence, loss, unacceptable delay, insertion, masquerade, and incorrect addressing, which current Ethernet frame structures struggle to address effectively, particularly in meeting the stringent error probability requirements of SIL3 and higher.
Innovation Solution
A communication method and device that calculates and transmits a data error detection code using a virtual sequence number, allowing for error detection without a dedicated field for the sequence number, and includes a safety protocol data unit and Ethernet frame structure that supports error detection and fail-safe states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated field for virtual sequence number is added to the packet structure, then error detection capability is improved, but packet structure complexity increases
Solution Approach 1:
The patent merges the virtual sequence number with the data error detection code calculation by incorporating the sequence number as an input parameter to the CRC calculation process. This combining approach allows the error detection code to implicitly contain sequence number information without requiring a separate dedicated field, thus improving error detection capability while avoiding additional packet structure complexity
Solution Approach 2:
The error detection code is designed to serve multiple functions simultaneously: it detects data corruption, verifies sequence number correctness, and identifies packet repetition. By making the error detection code multi-functional through the integration of sequence number in its calculation, the patent achieves enhanced reliability without increasing packet structure complexity
2Device complexity
If current Ethernet frame structure is used, then device complexity is reduced, but integrity requirements of industrial control systems cannot be satisfied
Solution Approach 1:
The patent modifies the error detection code calculation parameters by incorporating the virtual sequence number into the CRC calculation process. This parameter change transforms the standard error detection code into an enhanced version that can detect sequence errors and packet repetition, thereby satisfying industrial control system integrity requirements while maintaining compatibility with existing Ethernet frame structures
Data Source
AI summary
A first communication device calculates a data error detection code for detecting an error in data by using the data and a virtual sequence number, and generates a packet comprising the data and the data error detection code. The packet does not include the virtual sequence number which is used for calculating error detection. The first communication device transmits the packet to a second communication device.