About Add-On Instructions

Add-On Instructions are user-defined instructions. When you define an Add-On Instruction in a project it behaves similarly to a built-in instruction. You can define these instructions or they can be provided to you by someone else. An Add-On Instruction enables you to encapsulate your most commonly used logic as sets of instructions. These instructions let you easily reuse sets of commonly used instructions in your projects and share the instructions to promote consistency in all projects.

Create AOI logic using the standard Ladder, Function Block Diagram, and Structured Text language already available in the

Logix Designer

application. When created, an Add-On Instruction can then be used in any of the

Logix Designer

application routines.

For an Add-On Instruction, an output parameter defines data that is produced as a direct result of executing the instruction. An output parameter can only accept a tag as an argument, which is passed as a value back after execution. The data type for output parameters can be any valid atomic data type. The parameter's value is also accessible through a member of a tag, which is of the Add-On Instruction's data type. This value is updated as result of executing the Add-On Instruction.

Context views, which enable you to visualize the logic for your instruction for a specific instance of its use, simplify online troubleshooting of your Add-On Instructions. Auto-generated topic help also makes it easier for you to get the help you need for a successful implementation.

Finally, use the Add-On Instructions’ source protection capability to limit a user of your instruction to read-only access or to allow no access to the internal logic or local tags used by the instruction. This prevents unwanted changes to your instruction as well as protects your intellectual property.

In summary, Add-On Instructions enable you to:

Add-On Instruction Signature

The Add-On Instruction signature is checked at each download to verify that the Add-On Instruction parameters, local tags, and logic are unchanged. The instruction signature is also checked when the controller is verified (the Safety Signature ID is checked only at download). When the instruction signature has been generated, the

Logix Designer

application displays the instruction with a blue seal icon, as shown below.

 

When an instruction is sealed, the instruction signature is displayed on the faceplate of the instruction in the

Ladder Diagram Editor

and the

Function Block Diagram Editor

, as shown here:

You can turn on or off the display of the signature ID in the

Workstation Options

dialog box of the

Logix Designer

application. To access the Workstation Options dialog, choose Options from the Tools menu. See Viewing and Printing the Instruction Signature for more information.

You can also view the instruction signature and the safety instruction signature on the

Quick View

pane of the

Controller Organizer

and on the

Signature

tab of the

Instruction Definition Editor

dialog box.

Permission sets for Add-On Instructions