B&B Electronics VFG3000 - Manual - Manual (Page 68)

C REATING T AGS V LINX F IELDBUS G ATEWAY M ANAGER U SER M ANUAL
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• Tags are used within Fieldbus Gateway Manager to implement many advanced
features. If you want to use functionality such as alarms, triggers, data logging or
the web server, you will have to use tags, period. The formatting data from the
tag definition is typically required by all these features, so tags are mandatory for
their operation.
In other words, tags will automate many tasks during programming, saving you time. Even if
you decide not to use tags, many of the subsequent chapters of this manual refer to concepts
discussed in this chapter. You should thus read it thoroughly before proceeding.
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To create a tag, either click on one of the buttons displayed when the Tags icon is selected in
the left-hand pane of the Data Tags window, or use the new tag buttons on the toolbar. Either
way, a new tag will be added to the tag list. To edit the tag’s name, select the tag in the
left-hand pane, and type in the new name.
Tag names must conform to the following rules…
• Tag names may not contain spaces or punctuation.
• Tag names must start with a letter of the alphabet or an underscore.
• Subsequent characters must be digits, letters or underscores.
• Names must not exceed 24 characters in length.
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When a tag is selected in the left-hand pane, the right-hand pane will change to display a
number of tabs, each of which shows certain properties of the tag. Depending on the family
and type of the tag, different tabs may be present, and each tab may contain different fields.
No matter what kind of tag is selected, the first tab in the right-hand pane is always the Data
tab. This tab contains fields that indicate what data the tag is to represent, and how that data is
to be stored—and perhaps transferred to or from a remote device. The exact contents of the
tab will vary according to the family and type of the tag in question.
The second tab is always the Format tab. This indicates how the data in the tag is to be
formatted when shown on the Gateway’s display, or when presented to a user via any other
mechanism, such as a web page. The Format tab will take the same form for all tags of the
same type, such that all integer tags, for example, share the same set of properties.
The balance of the tabs define alarms and triggers for the tag. These are not included for
string tags or for arrays. Alarms are used to detect a condition that needs to be brought to the
operator’s attention, or simply to log the fact that the condition has occurred. Triggers operate
in a similar way, but instead of recording the condition, they are used to execute an action.