84 Publication 1756-PM004C-EN-P - October 2009
Chapter 4 Data Access Control
Constant Checkbox
Availability
The state of the Constant checkbox depends on a number of conditions.
Constant Variables
Dialog Box/Window Considerations
New Tag The Constant box is disabled if:
• the tag is an alias tag.
• the Factory Talk Security action is not enabled for changing
constant value property of a tag.
• you do not have permission to modify tag properties
(Factory Talk Security Tag Modify is denied.)
• the new tag is a Consumed tag.
• the tag’s ‘Data Type’ is not a data table-backed type.
• the tag’s ‘Usage’ setting is not ‘InOut’.
• redundancy controller is in any state that does not
allow changes.
• the controller is safety-secured and the tag is a safety tag.
(1)
• if the Scope is an equipment phase and the equipment phase
feature is not activated in the current license.
• the controller is in hard-run mode.
• the Add-On Instruction is in Source Protection mode.
(1)
If the controller is in safety-locked mode, only the safety tags will be disabled from being accessed, the
standard tags will have the same behavior as in the unlocked mode. The Constant value box will be disabled in
the Tag Properties dialog box only if the tag is a safety tag.
Tag Properties
Same considerations apply as for
New Tag
.
Tag Editor
Tag Monitor The value of a constant tag can be modified by using the Tag
Monitor window if you have both standard Tag: Modify Values
permission and Tag: Modify Constant Tag Values permission. You
cannot modify a constant value in any of the language editors or
any other tag browser. The icon in the Value column
indicates that you are changing a constant value tag’s value. Any
modifications to the values of constant tags are recorded in the
Controller Log for future reference.
For controller logging, see the Logix5000 Controllers Information
and Status Programming Manual, publication
1756-PM015
.
To Next Page
Loading...
Need help?
General
