CASS Documents

The templates of the CASS methodology can support consistent compliance of IEC 61508 and related standards.

The assessment of functional safety can be challenging and there are many aspects to consider and assess through the process. The CASS templates are designed to guide / support a competent assessor through various aspects of functional safety (dependent upon the specific form). Further details on CASS can be found on the CASS webpages of this website.

The CASS Scheme Association management team welcomes questions and feedback on the content and use of the CASS documents. Questions and feedback can be provided either directly to the CASS Scheme Association or via The 61508 Association (via contact us).

Important Note: Anyone is welcome to use the CASS templates, however, it must be realised that when performing conformity assessments, an appropriate level of competence is required of the assessor in the specific area that is being assessed. Please also review the CASS guide and especially the CASS disclaimer.

Conformity Assessment templates

The conformity assessment templates referenced in the above chart can be downloaded from the links below once they are available.

  • CASS-508-FSM for Functional Safety Management assessment to IEC 61508-1.
  • CASS-508-SLC for the overall Safety Lifecycle assessment to IEC 61508-1.
  • CASS-508-SYS for the E/E/PE System assessment to IEC 61508-2.
  • CASS-508-SUB for Element and Subsystem assessment to IEC 61508-2.
  • CASS-GUIDE-508-SW for guidance on Software assessment to IEC 61508-3 (full requirements).
  • CASS-508-SW for Software assessment to IEC 61508-3 (abridged for audit).

  • CASS TOES for FSM Assessment to IEC 61511-1:2016 (becomes CASS-511-FSM).
  • CASS TOES for the SIS Safety Life Cycle to IEC 61511-1:2016 (becomes CASS-511-SLC).
  • CASS-511-FSA for Functional Safety Assessment (FSA) to IEC 61511-1:2017 (IMPORTANT: Rename file to *.zip before use).

NOTE: The CASS-511-FSA file is upload as a *.docx file but is actually a *.zip file. Please rename before use, unzip it and you will find a *.xlsx file to support FSA's according to IEC 61511.

  • CASS-061 for the SCS safety lifecycle assessment (all aspects) to IEC 62061.

    Summary Papers

    The following documents summarise important requirement of IEC 61508 and related standards. Each paper targets a specific audience or a specific subject. The papers are intended for those needing a quick overview of Functional Safety as defined in IEC 61508.

    Technical papers and guides

    The following documents are intended for those needing a more in-depth consideration of technical issues. Where there is a companion in the section above, it is recommended they be studied together.

    Technical Paper for Public Comment (please use the "contact us" option if you wish to submit comments):
    Excel Spreadsheet Examples (e.g. for Functional Safety knowledge / personal development):

      Technical papers presented by members

      Technical papers presented by members of the 61508 association

      Achieving Hardware Fault tolerence: Paper presented by Mirek Generowicz of I&E Ststems Pty - Australia 

      Competency based assessment in Functional Safety: Paper presented by Mirek Generowicz of I&E Sysems Pty - Australia

      Cyber security - Paper presented by Peter Brown of Siemens Ltd.

      Demonstrating Prior Use: Paper presented by Dave Ransom

      Practical SIS Design and SIL verification: Paper presented by Paul Reeve of Silmetric

      Reassessing Failure Rate Data - Paper presented by Mirek Generowicz of I&E Ststems Pty - Australia 

      Systematic capability for Elements: Paper presented by Paul Reeve of Silmetric

      The use of an operator as a SIL1 component: Paper presented by Andrew Derbyshire of DNV Ltd

      New approach to SIL verification: Paper presented by Mirek Generowicz of I&E Systems Pty - Australia


      Miscellaneous downloads from 61508 Association.

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