Checklist to Develop a Safety Application Program

Were the programming guidelines followed during the creation of the safety application program?

Does the safety application program contain only a ladder diagram?

Does the safety application program contain only safety instructions?

Does the safety application program clearly differentiate between safety and standard tags?

Are only safety tags used for safety routines?

Have you verified that safety routines do not attempt to read from or write to standard tags?

Have you verified that no safety tags are aliased to standard tags and vice versa?

Is each safety output tag correctly configured and connected to a physical output channel?

Have you verified that all mapped tags have been conditioned in safety application logic?

Have you defined the process parameters that the fault routines monitor?

Have you sealed any safety Add-On Instructions with an instruction signature and recorded the safety instruction signature? Optional for one time use Add-On Instructions. Required Add-On Instructions are reused on different applications.

Did you measure potential alarm bursts during system commissioning and change the project if measured scan times are not acceptable?

Has an independent safety reviewer reviewed the program, if necessary?

Has the review been documented and signed?

If your application is SIL 3 or high-demand SIL 2, did you use the Redundancy Status bit (S:R) in program logic to monitor redundant system operation?