Because I/O Devices are often programmed independently of CitectSCADA, you can import, or link to, every the tag in an external data source. This means that you only have to define tag information once when you program your I/O Devices. You do not have to re-enter the same information again in CitectSCADA. Because the necessary information is already saved in an external data source, you can just import it or link to it.
There are two types of tags in the CitectSCADA variable database - linked tags and non-linked tags. When performing a tag import from Citect Explorer, only non-linked tags are updated. Linked tags remain unchanged. When performing a refresh or auto-refresh, only linked tags are updated. Non-linked tags remain unchanged. When performing a synchronization (Live Update), every tag for the I/O device are updated and linked.
CitectSCADA also lets you export tags to an external file, specifying the destination and format of your choice. You might then import this file into a third-party I/O Device programming package database, or simply use it as a backup.
Note: The simultaneous update of a tag name and its fields is only supported when importing via OFS. In every other case, if you attempt to simultaneously update a tag's name and fields, only the name will be updated. In this case update a tag name in a separate operation from updating its fields.