Rockwell Automation Logix5000 Controllers I/O and Tag Data Programming Manual - Manual (Page 71)

Data access control Chapter 4
Dialog Box/Window Considerations
New Tag The External Access list is unavailable if:
• The tag is an alias tag.
• The controller is user locked online.
Changing the tag type from base to alias also makes the External Access list unavailable. If you select a target for an alias tag in the Alias For
list, the External Access list remains unavailable, but the external access value for the target tag appears in the External Access list.
You can only change the external access value of an alias tag through its base tag.
Tag Properties The External Access list is unavailable if:
• You do not have permission to change the external access settings.
• The redundancy controller is in any state that does not allow changes.
• The controller is user-locked online from another computer.
• The controller is safety-locked and the tag is a safety tag.
• The tag scope is an equipment phase and the equipment phase feature is not activated in the current license.
• The tag is an alias tag.
• The controller is in hard-run mode.
Tag Editor The External Access list is unavailable if:
• You do not have permission to change the external access settings.
• The redundancy controller is in any state that does not allow changes.
• The controller is user-locked online.
• The controller is safety-locked and the tag is a safety tag. Only the safety tags’ External Access list is disabled.
• The tag scope is an equipment phase and the equipment phase feature is not activated in the current license.
• The tag is an alias tag.
• The controller is in hard-run mode.
• The row represents an expanded array dimension, bit, or data member.
For tags of Predefined (Atomic and Structural), Module-Defined Data Types and String, all of these tag members have the same external
access level because:
• They are all hard-coded to Read/Write and you can only view, not change, this value. You also cannot change external access for the data
type members.
• An external access change on the tag results in an update on all tag members.
For array tags, all elements:
• Must have the same external access level.
• Of all data members for predefined or module-defined data types have the same external access setting.
• Of each data member for user-defined type (UDT) and Add-On Instruction have the more restrictive external access setting between the
element external access setting and the external access setting of the member in the type definition.
You select the external access options for a tag—Read/Write (default), Read
Only, or None—from the Data Type Editor Properties pane.
User-defined type
considerations
Rock well Automati on Publication 1756- PM004E -EN-P - October 2014 71