Abstract
Recently, in various industrial fields, programmable electronic devices have been utilized for achievement of safety functions. This trend forced IEC (International Electrotechnical Commission) and ISO (International Organization for Standardization) to compile safety standards related to programmable electronic devices. The international standards of IEC 62061 and ISO 13849-1 specify requirements for machine safety control by use of probabilistic performance criteria of safety-related parts of machinery, i.e., safety integrity levels (SIL) and performance levels (PL). This paper examines the consistency between the SIL and PL. As a result, it became clear that the SIL and PL are not always consistent and the reason of this is the inequality between SFF and DC architecture constraints.
