Industrial Automation Knowledge Base

Issue When designing a Safety Instrumented Function (SIF), it is mandatory to define the Process Safety Time and ensure that the function will be executed within this time. According to IEC 61508, part 2, 7.4.3.2.5: The Process Safety Time (PST) is defined as the period between a failure occurring in the EUC (Equipment Under Control) or the EUC control system (with the potential to give rise to a hazardous event) and the occurrence of the hazardous event if the safety function is not performed. Resolution Engineers must carefully balance the scan cycle time and CPU bandwidth to ensure that all safety and non-safety tasks are executed efficiently. This often involves optimizing the program code and possibly upgrading hardware to meet the demands of stringent Process Safety Time (PST) requirements. Disclaimer The views and opinions expressed in this article are those of the author(s) and do not necessarily reflect the official policy or position of Schneider Electric.  

Warning Hazard of Electric Shock: Remove all power from all devices before removing any covers or doors of the system. Disconnect power at the device and at the power source. Electrostatic Discharge Required: Always discharge static electricity from your person by touching metal prior to handling any hardware. Failure to do so may result in damage to devices. Potential for Data Loss: The steps detailed in the resolution of this article may result in a loss of critical data if not performed properly. Before beginning these steps, make sure all important data is backed up in the event of data loss. If you are unsure or unfamiliar with any complex steps detailed in this article, please contact Product Support for assistance. Issue This KB Article describes the integration between the EcoStruxure Hybrid DCS control platform, WW Historian and Dream Report. Resolution See the attachment for more information.