Rockwell Automation FactoryTalk View Site Edition Users Guide - Manual (Page 202)

F ACTORY T ALK V IEW S ITE E DITION U SER ’ S G UIDE
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 An HMI tag with memory as its data source receives data internally, from
FactoryTalk View SE.
A memory tag can be used to store values internally.
About retentive memory tags
By default, the value of an HMI memory tag reverts to the initial value specified for the
tag, whenever the HMI server containing the tag is shut down and restarted.
To set up a memory tag to retain the last value it was set to, even after the HMI server is
shut down, in the Tags editor, select the Retentive check box for the tag.
A retentive memory tag will always have the last value it had prior to the HMI server
shutting down. In other words, the tag’s value will not revert to the initial value specified
for the tag.
Organizing HMI tags
To make HMI tags easier to work with, especially if the tag database is large, organize
related tags by establishing naming conventions for them, or by grouping them in folders.
Naming HMI tags
Establishing naming conventions for HMI tags makes using wildcard characters more
effective, when searching for and displaying tags during development and at run time.
Tag names can use up to 255 characters of the following types:
 A to Z (upper and lower case)
 0 to 9
 Underscore ( _ ) and dash ( – )
For HMI tags stored in folders, the folder name becomes part of the tag name, and the
backslash that separates folder names counts as one character.
Tag names can be mixed case. Tag names preserve upper and lower case for readability
but they are not case sensitive. For example, the tag name MixerValve1 is the same as
mixervalve1.
Enclosing tag names in brackets
In an expression, tag names that start with a number or contain a dash must be enclosed in
brackets, for example, {N33-0}.
Also use brackets with wildcard characters to represent multiple tags in an expression, for
example, {alarm*}.