Importing tags from an external data source lets you halve your data entry time. Instead of entering your tag information once when you program your I/O Device and once when you configure your project, you can program your I/O Device, then import the tags straight into CitectSCADA, where they are treated as regular tags. (CitectSCADA automatically creates variable tag records for every tag in the I/O Device.)
Note:CitectSCADA only supports the use of alphanumeric characters, the backslash and underscore characters (see Tag name syntax). Any other characters will be converted to underscores on import. This may result in Duplicate Tag errors on compilation.
Like linking, the importing of tags is an I/O Device specific operation: you import the tags for a particular I/O Device. Unlike linking, however, imported tag records are not linked in any way to the tags in the external data source. Therefore, importing is typically a one-time operation. To update imported tags, you need to import them again.
Note: Tags will be imported into the project in which the selected I/O Device is defined. This could be either the project selected in the Explorer, or in one of its included projects.
For most external data sources, the import process involves two steps. First you export the data from the I/O Device to a format that CitectSCADA can read, then you import the database into CitectSCADA. However, tag data saved using Mitsubishi or Unity FastLinx can be read directly by CitectSCADA. This means that no export is necessary.
Some characteristics of the import are defined in
the format files in the
directory (with the extension
.fmt). There is one format file for each
database type, and each file specifies how external data is
converted to CitectSCADA
variable data. In general, imported tags are either added to the
database if the tag does not already exist, or updated if the tag
exists. However, if a field is listed in the
[EditableFields] section of the format file
corresponding to the import database type:
For example, if a tag has 10 fields to be imported and 5 of them are listed in the [EditableFields] section of the format file, then if the tag already exists in CitectSCADA the tag will be updated with the external values for the 5 fields that are listed in [EditableFields]. If the tag does not already exist then the tag will be created with the external values for every 10 fields.
Fields marked as editable in this way can be changed by CitectSCADA. To prevent internal changes being lost, changes to these fields in the external database are ignored.
Note: If the external database supports to LiveUpdate and the LiveUpdate Link has been selected for the I/O Device, existing CitectSCADA tags will be synchronized with the external database and the tags will be updated for the imported fields regardless of whether it is marked as an editable field. An I/O Device configured as Linked or Auto-refreshed Linked will behave as in a normal import and will not update fields marked as editable.
When you import tags into CitectSCADA, you have two options for dealing with existing tags:
If you import a data source that is already linked, every tag in the data source are duplicated. That is, you will have two copies of each tag: one local and one linked.
See Imported Tags for information about levels of support between Unity and CitectSCADA.
Some properties defined for the external tags will not be relevant to CitectSCADA. Also, some will not be in a format that CitectSCADA can read. To define what information is copied to CitectSCADA's variable tags database and how this information is to be converted, you need to edit the I/O Device's format file.
To import variable tags from an external database: