Rockwell Automation Logix5000 Controllers Add-on Instructions Programming Manual - Manual (Page 34)

Chapter 1 Designing Add-On Instructions
Tip: When you are using your Add-On Instructions, the Visible setting may be overridden in Function Block
Diagram routines if the parameter is not required or already wired. Overriding the visibility at the
instruction call does not affect this definition configuration.
Using standard and safety tags
When creating a safety Add-On Instruction, follow these guidelines for standard
and safety tags:
• Standard tags may not be used as Input, Output, or InOut parameters of a
safety Add-On Instruction.
• Safety tags may be used as Input parameters for standard Add-On
Instructions.
Data access control
In RSLogix 5000 software, version 18 and later, you can prevent programmatic
modification of InOut parameters by designating them as constants. You can also
configure the type of access to allow external devices, such as an HMI, to have to
your tag and parameter data. You can control access to tag data changes with Logix
Designer application by configuring FactoryTalk security.
34 Rockwell Automation Publication 1756-PM010F-EN-P - October 2014