About Add-On Instructions

With Add-On Instructions, you can create new instructions for sets of commonly-used logic, provide a common interface to this logic, and provide documentation for the instruction.

Add-On Instructions are intended to be used to encapsulate commonly used functions or device control. They are not intended to be a high-level hierarchical design tool. Programs with routines are better suited to contain code for the area or unit levels of your application.

These are some benefits to using Add-On Instructions:

• Reuse code
– You can use Add-On Instructions to promote consistency between projects by reusing commonly-used control algorithms.
– If you have an algorithm that will be used multiple times in the same project or across multiple projects, it may make sense to incorporate that code inside an Add-On Instruction to make it modular and easier to reuse.

• Provide an easier to understand interface
– You can place complicated algorithms inside of an Add-On Instruction, and then provide an easier to understand interface by making only essential parameters visible or required.
– You can reduce documentation development time through automatically generating instruction help.

• You can export an Add-On Instruction to an .L5X file that can then be imported into another project. You can also copy and paste between projects.

• Protect intellectual property
– You can place your proprietary code inside of an Add-On Instruction, then use Source Protection to prevent others from viewing or changing your code.

• Simplify maintenance
– You can simplify code maintenance because Add-On Instruction logic, monitored in the Logix Designer application, animates with tag values relative to that specific instance of the Add-On Instruction.

• Track revisions, a chang history, and easily confirm instruction functionality with high-integrity Add-On Instructions
– You can add an instruction signature to your Add-On Instruction, which generates a unique identifier and prevents the instruction from being edited without resulting in a change to the signature.

An Add-On-Instruction can be used across multiple projects. You can define the instructions, the instructions can be provided to you by someone else, or they can be copied from another project.

Once defined in a project, they behave similarly to the built-in instructions already available in the Logix Designer application. They appear on the instruction toolbar and in the instruction browser for easy access, just like built-in Logix Designer application instructions.

Like standard Add-On Instructions, safety Add-On Instructions let you encapsulate commonly-used safety logic into a single instruction, making it modular and easier to reuse. In addition to the instruction signature used for high-integrity Add-On Instructions, safety Add-On Instructions feature a SIL 3 safety instruction signature for use in safety-related functions up to and including SIL 3.


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