Rockwell Automation Logix5000 Controllers Add-on Instructions Programming Manual - Manual (Page 30)

Chapter 1 Designing Add-On Instructions
Attribute Name Data Type Attribute Description
MajorRevision DINT Major revision number of the Add-On Instruction
MinorRevision DINT Minor revision number of the Add-On Instruction
Name String Name of the Add-On Instruction
RevisionExtendedText String Text describing the revision of the Add-On Instruction
Vendor String Vendor that created the Add-On Instruction
LastEditDate LINT Date and time stamp of the last edit to an Add-On Instruction
SignatureID DINT 32-bit instruction signature value
SafetySignatureID DINT 32-bit safety instruction signature value
For more information on using GSV and SSV instructions, refer to the Logix5000
Controllers General Instructions Reference Manual , publication 1756-RM003.
Consider the following information when you are creating parameters.
Passing arguments to parameters by reference or by value
The following information will help you understand the differences between
passing argument tags to parameters by reference or by value.
Aspect By Value (Input or Output) By Reference (InOut)
Value Synchronous—the argument's value does not change during
Add-On Instruction execution.
Asynchronous—the argument's value may change
during Add-On Instruction execution. Any access by
the instruction's logic directly reads or writes the
passed tag's value.
Performance Argument values are copied in and out of the parameters of
the Add-On Instruction. This takes more time to execute a call
to the instruction.
Parameters access argument tags directly by
reference, which leads to faster execution of
instruction calls.
Memory usage Most amount. Least amount.
Parameter data types supported Atomic (SINT, DINT, INT, REAL, BOOL). Atomic, arrays, and structures.
Considerations when
creating parameters
30 Rockwell Automation Publication 1756-PM010F-EN-P - October 2014