Rockwell Automation Publication SAFETY-AT125C-EN-P - February 2022 15
Enabling Switch with an Integrated Safety Controller and a POINT Guard I/O Safety Module Safety Function Application Technique
A message has been added about the mission time of enabling switch elements (EL). An estimated annual number of 8760 cycles, one per
hour, 24 hours a day, 365 days a year, was used to calculate the MTTFd. The note indicates that at that rate of use, the enabling switch must
be replaced after 11.42 years of use.
Verification and Validation Plan
Verification and validation play important roles in the avoidance of faults throughout the safety system design and development process. ISO
13849-2 sets the requirements for verification and validation. The standard calls for a documented plan to confirm that all safety functional
requirements have been met.
Verification is an analysis of the resulting safety control system. The Performance Level (PL) of the safety control system is calculated to
confirm that the system meets the required Performance Level (PLr) specified. The SISTEMA software is typically used to perform the
calculations and assist with satisfying the requirements of ISO 13849-1.
Validation is a functional test of the safety control system to demonstrate that the system meets the specified requirements of the safety
function. The safety control system is tested to confirm that all safety-related outputs respond appropriately to their corresponding safety-
related inputs. The functional test includes normal operating conditions and potential fault injection of failure modes. A checklist is typically
used to document the validation of the safety control system.
Before validating the GuardLogix Safety System, confirm that the safety system and safety application program have been designed in
accordance with the controller safety reference manuals that are listed in Additional Resources
, and the GuardLogix Safety Application
Instruction Set Reference Manual, publication 1756-RM095
.
For a validation checklist, see the attached spreadsheet.
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