User manual

60 Publication 1756-RM093F-EN-P - January 2010
Chapter 6 Safety Application Development
Safety Validation
An independent, third-party review of the safety system may be
required before the system is approved for operation. An
independent, third-party certification is required for IEC 61508 SIL 3.
Lock the GuardLogix Controller
The GuardLogix controller system can be safety-locked to protect
safety control components from modification. The safety-lock feature
applies only to safety components, such as the safety task, safety
programs, safety routines, safety tags, safety Add-On Instructions,
safety I/O, and safety task signature. However, safety-locking alone
does not satisfy SIL 3 requirements.
No aspect of safety can be modified while the controller is in the
safety-locked state. When the controller is safety-locked, the following
actions are not permitted in the safety task:
• Online or offline programming or editing
• Forcing safety I/O
• Data manipulation (except through routine logic or another
GuardLogix controller)
• Creating or editing safety Add-On Instructions
• Generating or deleting the safety task signature
The default state of the controller is safety-unlocked. You may place
the safety application in a safety-locked state regardless of whether
you are online or offline, and regardless of whether you have the
original source of the program. However, no safety forces or pending
safety edits may be present. Safety-locked or -unlocked status cannot
be modified when the keyswitch is in the RUN position.
To provide an additional layer of protection, separate passwords may
be used for safety-locking or -unlocking the controller. Passwords are
optional.