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Glossary
safety program A safety program has all attributes of a standard program, except that it can be
scheduled only in a safety task. The safety program consists of zero or more
safety routines. It cannot contain standard routines or standard tags.
safety protocol A network communication method that is designed and certified for transport
of data with high integrity.
safety routine A safety routine has all attributes of a standard routine except that it is valid
only in a safety program and that it consists of one or more instructions
suitable for safety applications. (See
Appendix A
on
page 69
for a list of Safety
Application Instructions and standard Logix Instructions that can be used in
safety routine logic.)
safety tags A safety tag has all attributes of a standard tag except that the GuardLogix
controller provides mechanisms that are certified to SIL 2 or SIL 3 to help
protect the integrity of their associated data. They can be program-scoped or
controller-scoped.
safety task A safety task has all attributes of a standard task except that it is valid only in a
GuardLogix controller and that it can schedule only safety programs. Only one
safety task can exist in a GuardLogix controller. The safety task must be a
periodic/timed task.
safety task period The period at which the safety task executes.
safety task reaction time The sum of the safety task period plus the safety task watchdog. This time is
the worst case delay from any input change that is presented to the GuardLogix
controller until the processed output is available to the producing connection.
safety signature A value, which the firmware calculates, that uniquely represents the logic and
configuration of the safety system. It is used to verify the integrity of the safety
application program during downloads to the controller.
safety task watchdog The maximum time that is allowed from the start of safety task execution to its
completion. Exceeding the safety task Watchdog triggers a nonrecoverable
safety fault.
set system value (SSV) A user application instruction that sets controller system data.
SIL claim limit (SILCL) Maximum SIL that can be claimed for a SRECS subsystem in relation to
architectural constraints and systematic safety integrity. (from IEC 62061)
standard Any object, task, tag, program, or component in your project that is not a
safety-related item (that is, standard controller refers generically to a
ControlLogix or CompactLogix controller).
standard component Any object, task, tag, program, and so on, that is not marked as being a safety-
related item.
standard controller As used in this document, standard controller refers generically to a
ControlLogix or CompactLogix controller.
106
Rockwell Automation Publication 1756-RM012B-EN-P - April 2018
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