Rockwell Automation Publication 1791ES-UM001G-EN-P - November 2016 151
Appendix B
Safety Data
This appendix lists calculated values for probability of failure on demand
(PFD), probability of failure per hour (PFH), and mean time to failure
(MTTF). PFD and PFH calculations comply with IEC 61508, edition 2,
2010.
Calculated Values
Calculated values of probability of failure on demand and probability of failure
per hour appear in Table 65
. These values must be calculated for the devices
within the system to comply with the SIL level required for application.
You are responsible for following the requirements of ISO 13849-1:2008 to
assess performance levels in your safety system.
Functionally test every I/O module by individually toggling each input point
and verify that the controller detects it within the proof test interval.
Additionally, individually toggle each output point with the controller and
verify that the output point changes state.
For more information, see the appropriate GuardLogix® Safety Reference
Manual, which is listed in the Additional Resources on page 10
.