Rockwell Automation Logix5000 Controllers I/O and Tag Data Programming Manual - Manual (Page 73)

Data access control Chapter 4
• If the member’s data type is User-defined and the child-member has a
different external access level from its parent, the more restrictive external
access level applies to the child-members.
The following table describes the conditions in which the External Access
column is unavailable.
To pick Considerations
Change existing
data type
The External Access column is unavailable if:
• You do not have permission to change the external access settings
(2) .
• The redundancy controller is in any state that does not allow changes.
• The data type is applied to tags and the controller is online.
Tip: Data type size is not affected by the external access attribute.
Predefined, module-defined,
Strings type
The External Access column is always visible but unavailable. The Set External Access
entry is added to the bottom of the row header context menu, but it is always unavailable.
(2) If you have User-defined Data Type Modify permission, you also can modify external access of a User-defined data type.
You can use external access settings with parameters and local tags of Add-On
Instructions. For example, if you define an input parameter with external access of
read only, the member that represents that parameter in the Add-On Instruction
data type cannot be written.
The following table describes the external access options for various Add-On
Instruction parameters and tags.
Add-0n Instruction Parameters and Tags External Access Options
Local tag
Read/Write
Read Only
None
Input parameter
Output parameter
EnableIn parameter
Read Only
EnableOut parameter
InOut parameter Not Applicable
You can choose the external access for an Add-On Instruction tag from the list on
the New Add-On Instruction Parameter or Local Tag dialog box or from the
External Access column on the Tag Editor.
Add-on instructions
external access
considerations
Rock well Automati on Publication 1756- PM004E -EN-P - October 2014 73