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Using an Add-On Instruction
Programming Tips when
Using an Add-On
Instruction
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This table describes programming tips for you to reference when using
Add-On Instructions.
Topic
Description
Instruction Help
Use the instruction help to determine how to use the
instruction in your code.
Ladder Rungs
In a Ladder rung, consider if the instruction should be
executed on a false rung condition. It may improve
scan time to not execute it.
Data Types
A data type defined with the Add-On Instruction is
used for the tag that provides context for the execution
from your code. A tag must be defined of this type
Parameter on the call to the instruction.
Indexed Tag
You can use an indirect array indexed tag for the
Instruction instance. One drawback is that you cannot
monitor Add-On Instruction using this as a data
context.
Passing Data
• Input and Output Parameters are passed by value.
• InOut Parameters are passed by reference.
Programmatically
Accessing a Parameter
Follow these procedures for any language when you want to access a an
Add-On Instruction Parameter that isn't available on the instruction face by
default.
The following procedures demonstrate how to use the Jog parameter of the
Motor Starter Add-On Instructions.
Publication 1756-PM001I-EN-P - January 2007