Delete A Tag

About this task

Historian allows you to delete and permanently delete tags. When a tag is deleted, it is removed from the tag database, but all data for that tag is retained in the archive and the tag name cannot be re-used. Since the tag data is still available from the archive, you can still reference that tag from within a calculation formula, for example, or by using the Excel Add-In.

When a tag is permanently deleted, all the data for that tag is removed from the archive and the tag name is available for reuse. For more information, see Permanently Deleting Tags.

Whenever you delete tags, the following collectors reload only the modified tag(s) without restarting the collectors.
  • OPC Collector
  • iFIX collector
  • Calculation collector
  • Simulation Collector
  • Server to Server Collector
  • PI Collector
  • PI Distributor

By default, the On-line Tag Configuration Changes option is enabled, which allows a tag to stop and restart data collection without restarting the collector. If you disable the On-line Tag Configuration Changes option, any changes you make to the tags do not affect collection until after you restart the collector. To enable or disable the On-line Tag Configuration Changes option, select Advanced on the Collector Maintenance page. To restart a collector, stop and start the collector service or executable.

Restarting the collector stops and restarts the tag(s) collection and may record bad data samples to the collection. All the collector configuration changes done within a 30 second time frame are batched up together. To collect the modified data faster, update/modify a small set of tags at a time. If the modified tags get zero bad markers and available runtime values at the same time, then precedence is given to available runtime values instead of zero bad markers.

Tip:
  • To collect the modified data faster, update/modify a small set of tags at a time.
  • When updating large sets of tags at the same time, best practice is to disable the On-line Tag Configuration Changes option and restart the collector after modification.

Procedure

  1. In the Tag Maintenance page, select a tag from the list in the left-hand window of the page.
    The tag information for that tag fills in the right-hand column.
  2. Select the Delete button at the bottom right of the page.
    The Delete Tag window shown in the following figure appears.

  3. Select the Remove Tag from System option and select OK.
    This removes the tag from the Tag Data-base but retains any data for that tag in the archive.
    Note: Since the tag data is still available from the archive, you can still reference that tag, for example, from within a calculation formula, or by using the Excel Add-In.
    A message box appears asking you to confirm the deletion.
  4. Select Yes to delete the tag.