Communication Design of Low Residual Error Probability Based on Function Safety

Abstract

As the scale of petrochemical industry and electric power industry grows, the safety instrumented system (SIS) becomes more complex and the safety requirements of SIS are more rigorous. Generally, SIS is composed of sensors, actuators, logical control devices, and communication systems. The design of communication system is considered as a key part of SIS designing and residual error probability is an important index to evaluate safety of communication. Therefore, it is crucial to come up with a method to design a communication system with low residual error probability. On the basis of design experience of FirmSys which is a safety integrity level (SIL) 3 safety platform developed by China Techenergy Cooperation (CTEC) and according to the standard IEC 61508, this article presents necessary design measures to reach low residual error probability including data integrity assurance, diagnostic techniques, the number of bits in the block, etc. And also it provides the design method of each element. This design method is applicable to the design of the communication protocol which can meet the functional safety requirement.