76 Rockwell Automation Publication 1756-RM012B-EN-P - April 2018
Appendix B Create and Use a Safety Add-On Instruction
The Safety Instruction
Signature
When a sealed safety Add-On Instruction is downloaded for the first time, a
safety instruction signature is automatically generated. The safety instruction
signature is an ID number that identifies the execution characteristics of the
safety Add-On Instruction.
SIL 2 or SIL 3 Add-On
Instruction Qualification Test
Safety Add-On Instruction tests must be performed in a separate, dedicated
application to verify that unintended influences are minimized. You must
follow a well-designed test plan and perform a unit test of the safety Add-On
Instruction that exercises all possible execution paths through the logic,
including the valid and invalid ranges of all input parameters.
Safety Validate Add-On
Instructions
An independent, third-party review of the safety Add-On Instruction can be
required before the instruction is approved for use. An independent, third-
party validation may be required for functional safety certification.
Create Signature History
Entry
The signature history provides a record for future reference. A signature
history entry consists of the instruction signature, the name of the user, the
time stamp value, and a user-defined description. Up to six history entries can
be stored. You must be offline to create a signature history entry.
Export and Import the Safety
Add-On Instruction
When you export a safety Add-On Instruction, choose the option to include
all referenced Add-On Instructions and user-defined data types in the same
export file. By including referenced Add-On Instructions, you make it easier to
preserve the signatures.
When importing Add-On Instructions, consider these guidelines:
• You cannot import a safety Add-On Instruction into a standard
controller project.
• You cannot import a safety Add-On Instruction into a safety controller
project that has been safety-locked or one that has a safety signature.
• You cannot import a safety Add-On Instruction while online.
• If you import an Add-On Instruction with an instruction signature into
a project where referenced Add-On Instructions or user-defined data
types are not available, you may need to remove the signature.
For more information, see the Import/Export Project Components
Programming Manual, publication 1756-PM019
.
TIP The Signature Listing report in the Studio 5000 Logix Designer application prints
the instruction signature, the time stamp, and the safety instruction signature. To
print the report, right-click Add-On Instruction in the Controller Organizer and
choose Print>Signature Listing.
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