As the growth of reliability of PLCs and the amount of automation in various machinery has increased significantly, the substance of safety equipment reliability has grown in the absence of human control. These factors have led to an increase in the demand for safety-related PLCs. The complexity and size of the software-based control applications grows and so does the importance to be able to produce safe software code. The requirements for machine safety posed by the national and international laws are intricate and many industrial standards have been formed to facilitate designing machinery that meet these requirements. This thesis concentrates on these standards and the recommendation and requirements they pose on safety analysis, design process, operating systems, tools and programming languages.Through charting various safety-related requirements it becomes clear that compared to non-safety-related projects, safety-related projects require many times more documentation on made design choices, analysis and implementations. The requirements for this large amount of documentation are based on the need to be able to provide evidence on sufficient rigour and comprehensiveness of the made safety analyses and implementation quality. To be able to control all this information this thesis recommends forming information databases for companies designing such machinery. These databases would facilitate finding and updating all the relevant information from safety standards to project-specific documents in one place.
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