Allen-Bradley 1756-L65 ControlLogix 5565, Programming Manual

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Rockwell Automation Publication 1756-PM004D-EN-P - September 2012 73
Data Access Control Chapter 4
User-defined Type
Considerations
The three external access options—Read/Write (default), Read Only, None—are
chosen from the External Access column on the Data Type
dialog box.
Three external access rules apply for members of User-defined data types.
•
You can only set external access for the top members of that User-defined
data type. External Access cells for the child-members are disabled on the
User-defined Data Type dialog box.
•
If the member’s data type is Predefined structural, Module-defined, or
String, you cannot set external access of child-members. The external
access level of the parent member is given to its child-members.
•
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 is applied.
The following table describes the conditions in which the External Access
column is disabled.
Add-On Instructions External
Access Considerations External Access settings can be used with parameters and local tags of Add-On
Instructions. For example, if an input parameter is defined with external access of
read only, the member that represents that parameter in the Add-On Instruction
data type cannot be written.
Topic Considerations
Modify existing
data type
The External Access column is disabled if:
• you do not have permission to change the external access settings.
(1)
• the redundancy controller is in any state that does not allow changes.
• the data type is applied to tags and the controller is online.
Note: Data type size is not affected by the external access attribute.
(1)
If you have User-defined Data Type Modify permission, you also can modify external access of a User-defined data type.
Predefined,
module-defined, Strings
type The external access column is always visible but disabled. The Set External Access entry
is added to the bottom of the row header context menu, but it is always disabled.