Programmatic Access to Data

Input and Output parameters and local tags are used to define an instructiondefined data type. Each parameter or local tag has a member in the data type, although local tag members are hidden from external use. Each call to an Add-On Instruction uses a tag of this data type to provide the data instance for the instruction's execution.

The parameters of an Add-On Instruction are directly accessible in the controller's programming via this instruction-defined tag within the normal tagscoping rules.

Local tags are not accessible programmatically through this tag. This has impact on the usage of the Add-On Instruction. If a structured (including UDTs), array, or nested Add-On Instruction type is used as a local tag (not InOut parameters), then they are not programmatically available outside the Add-On Instruction definition.