Point Updates to which Compression Settings do not Apply

If you Apply Historic Data Compression Settings to a point, ClearSCADA compares the update that it last stored historically for the point and the next update that is marked for compression. If any of the following point attributes differ between the two values, ClearSCADA ignores any Compression settings and automatically stores the latest update historically:

• State
• Quality
• The Reason for the point update (for example, Timed Report, or Current Update)

  ClearSCADA typically stores point updates that change due to an Override or Release Override pick action, as the reason for these updates typically differs from the reason for the previously stored value.

• Status
• M/S State (only applies to analog points that are on systems on which Master Station Alarm Limits are enabled).

Additionally, ClearSCADA also stores any ‘out of sequence’ data historically. Out of sequence data comprises values that are time stamped with an earlier time to the previously stored value.

You can determine why ClearSCADA has stored an update historically, by looking at the Historic List for the point. Each of the above attributes are displayed in separate columns on the List.

For further information on Historic Lists, see Historic Lists in the ClearSCADA Guide to Lists.