Safety System Principles

You must read, understand, and fulfill safety requirements as described in this publication before you operate a SIL 2/PLd or SIL 3/PLe safety system.
FactoryTalk® Design Studio™
 is certified to clause 7.4.4 of IEC 61508-3 Edition 2 only when used according to this publication.
You, the user, own, specify, design, develop, test, and validate any safety system that you create with
FactoryTalk® Design Studio™
.
You must be trained and experienced in safety applications before you develop the application program for the intended SIL 2 or SIL 3 system. You must follow good design practices.
  • Use functional specifications, including flowcharts, timing diagrams, and sequence charts.
  • Perform a review of safety task logic.
  • Perform application validation. As you develop your safety application, consider the following important notes.
IMPORTANT:
  • FactoryTalk® Design Studio™
     is certified to clause 7.4.4 of IEC 61508-3 Edition 2 and can be used during the coding lifecycle of applications and also as an aide in the module test, integration test, and validation test lifecycle phases. As a result, no additional justification for its use during those lifecycle phases is required. If, however, other tools are used, either on their own or with
    FactoryTalk® Design Studio™
    , additional justification for those other tools is required. It is your responsibility to verify that other offline tools that are used during all lifecycle phases are selected as a coherent part of the software development activities.
  • You are responsible to conduct an assessment to determine the level of reliance that is placed on
    FactoryTalk® Design Studio™
     and the potential failure mechanisms that can affect the executable software when the application is used in a manner other than what is specified in the product documentation.
  • You must verify that all programming and configuration information that is entered into
    FactoryTalk® Design Studio™
    , and deployed to the controller, meets the requirements for your application.
  • When connecting to a safety controller, the application compares the serial number of the controller with the last known serial number an application was deployed to. A warning displays, which you must acknowledge, if the application detects a mismatch. To avoid faults, verify the serial number with the product label on the safety controller. Any other means of verification requires confirmation of the accuracy of the serial number.
  • As required by the safety integrity level, the software, or design representation, the characteristics of the application must be compatible with the features
    FactoryTalk® Design Studio™
     supports and the safety controllers that are listed in the Preface.
  • As required by the safety integrity level, the software or design representation must be compatible with the features that are supported in
    FactoryTalk® Design Studio™
     and safety controllers. It is your responsibility to verify that the desired software and design representation are supported in
    FactoryTalk® Design Studio™
     and safety controllers. For example, if the design is represented in a flowchart format, it is your responsibility to convert that design to a ladder diagram.
  • The use of third-party, internally developed, or artificial intelligence tools to generate logic automatically to import into
    FactoryTalk® Design Studio™
     for compilation and deployment to a controller requires assessment of the tool's suitability at the point in the development cycle where it is selected.
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