Variable-Level Integrity Checks for Process Control Communications
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Solution Overview
Problem
In process control environments, especially in safety systems, the existing methods lack the ability to verify the integrity of variable values on a variable-by-variable basis, leading to potential errors and unreliable communications, which can exceed acceptable thresholds for safety standards.
Innovation Solution
The described methods and systems enable process control devices to transmit and receive device variable values with embedded data integrity checks, allowing receiving devices to verify the integrity of the values on a variable-by-variable basis by calculating and comparing data integrity checks using a seed, ensuring that only verified values are updated or acted upon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data integrity checks are implemented at the message level only, then the communication system maintains simplicity, but the reliability of individual variable values cannot be verified
Solution Approach 1:
The patent segments the data integrity verification process from message-level to variable-level by introducing individual integrity check fields for each variable within a message. This allows the receiving device to verify and accept or reject individual variable values independently, rather than treating the entire message as a single unit. The segmentation enables partial message acceptance where some variables are verified while others may be rejected, thereby improving reliability without requiring complete message retransmission.
2Reliability
If variable-by-variable integrity verification is implemented, then the trustworthiness of received values improves, but the processing time and computational overhead increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and embedding the integrity check value for each variable at the time of message construction, rather than performing verification calculations after message receipt. The sending device computes the integrity check (such as a checksum or cryptographic hash) for each variable and includes it in the transmitted message. This shifts the computational burden to the sending device and allows the receiving device to perform simpler comparison operations, reducing verification processing time.
3Reliability
If all variable values in a message are accepted together, then the ease of operation is maintained, but errors in individual variables cannot be detected
Solution Approach 1:
The patent implements local quality by enabling selective acceptance of variable values based on their individual integrity verification results. Each variable in the message can be independently evaluated - variables with valid integrity checks are accepted and updated, while variables with failed checks are rejected and left unchanged or marked for retransmission. This localized verification approach allows the system to maintain ease of operation for valid variables while detecting and isolating errors in specific variables without requiring manual intervention for the entire message.
Data Source
AI summary
The described methods and systems enable process control devices to transmit and receive device variable values in a manner that enables the receiving device to verify the integrity of the received values on a variable-by-variable basis. To facilitate verification of integrity, any desired number of variables in a message may have a data integrity check in the message. For each received value that has a data integrity check, the receiving device can calculate its own data integrity check based on the received value and a seed (known to both the transmitting and receiving devices), which it can then compare to the received data integrity check to verify if the received value has been altered during communication.