ProSoft Technology ProLinx S3964R User Manual download pdf (Page 38)

38 Publication LOGIX-AP010B-EN-P - May 2010

Chapter 2 Software Conversions - Program Structure

More details on programming in RSLogix 5000 software can be found in the

ControlLogix User Manual, publication 1756-UM001

Function Blocks/Add-On

Instructions

RSLogix 5000 software allows programming of Add-On Instructions that can

replace and enhance the functionality of Step 5 Function Blocks.

The Add-On Instruction functionality allows the combination of commonly

used logic into one function that can be called and executed multiple times as

required in the program.

Add-On Instructions are programmed by Ladder Logic, Structured Text, or

Function Block Diagrams.

The Add-On Instruction, like the Step 5 Function Block can be assigned input

and output parameters.

Unlike Step 5, an Add-On Instruction can also have an InOut Parameter to

define data used as input and output during instruction execution. An InOut

Parameter is passed by reference, meaning the logic deals directly with the tag

passed to the instruction. InOut parameters can be any data type because they

are passed by reference. Any data structures or arrays that must be passed to

an Add-On Instruction can be done with InOut Parameters.

The Add-On Instruction will automatically maintain a change history by

recording a timestamp and the Windows user name at the time of the change.

This is not available with Step 5 Function Blocks. The Add-On Instruction

also automatically generates help files.

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ProSoft Technology ProLinx S3964R User Manual Page 38