The Research On International Standards For Functional Safety

International standard IEC61508, functional safety of electrical/electronic/ programmable electronic safety-related systems, provides an approach composed of new theories and measures to ensure safety. At present this approach has been widely accepted as the general principle for industrial safety assurance by process industry, machine industry, pharmacy, traffic, etc. However, this app-roach is not familiar with domestic safety field. There is no corresponding nation-al standard brought forward, and few application of the standard to ensure industrial safety in our country. Actually there is no mandatory standard for the safety case in industry, so safety production of most factories in our country is not implemented, and safety product development are blocked.This paper is a general introduction of IEC61508 base on interpreting the concept and theory of the standard, analyzing international applications of the standard, summarizing techniques for hardware/software reliability design and evaluation, and presenting general safety management process. The paper can be summarized as following:(1) Introducing the background and progress of the international standards. After comparing to the international research and application of the standards, drawbacks in our research and application are revealed.(2) Introducing the primary content of IEC61508 and IEC61511, interpreting the main concepts and theories of IEC61508, and summarizing the features of the standard.(3) Dividing the application process of the standard into three parts, stating the techniques in every part respectively.(4) Summarizing the requirements for hardware in IEC61508, presenting an approach to evaluate the hardware product and to make the product to meet the requirement of the standard.(5) Interpreting the requirements for software in IEC61508, through presenting somedefects in the requirements, proposing a refined developing process for software, include requirement specification, design and implementation. At last, after taking the advantages of the present safety PLC techniques and the refined developing process, the techniques needed to implement the safety PLC software are summarized. Then, a primary solution for safety PLC is presented.