Research on the integrated failure analysis method of safety and security of fieldbus transmitters

Fieldbus transmitters are commonly used in modern industrial productions, particularly in Safety Instrumented Systems (SIS). Safety and security are critical considerations in the design and operation of these transmitters. Previous research has tended to address safety issues and security issues separately, but with the increasing complexity of network technology, it is important to analyze them simultaneously. In this paper, a systematic framework for comprehensively analyzing random failures and cyber-attack failures is proposed. The framework adopts the FMEA-IMEA method, which combines Failure Modes and Effects Analysis (FMEA) and Intrusion Modes and Effects Analysis (IMEA), to analyze failure modes and effects of fieldbus transmitters. In addition, by extending Reliability Block Diagrams (RBD), the impact of random failures and cyber-attack failures on fieldbus transmitters is quantitatively determined. At the same time, calculation approach of the residual error rate (RER), Component counting method, and Monte Carlo are used to determine random failure rate and cyber-attack failure rate. Using fieldbus pressure transmitter and fieldbus temperature transmitter as examples, the results demonstrate that security issues can significantly impact the safety integrity level. In fact, the safety integrity level is reduced from SIL3 to SIL1 when cyber-attacks are considered. Compared to existing FMEA, the proposed approach offers a more comprehensive analysis of random failures and cyber-attack failures in fieldbus transmitters.