Use the fields within the Historic Data Filter section of the DDE tab to specify the type of data that Geo SCADA Expert is to store historically for an analog point.
Use the Historic Data Filter section in conjunction with the Historic tab, which defines whether the server stores values historically for the point, and whether any unnecessary data is filtered out to reduce storage requirements (see Defining Historic Details for a Point in the Geo SCADA Expert Guide to Core Point Configuration).
The Geo SCADA Expert server retrieves and processes the current data values from the DDE server(s) that it monitors. Use the check box within the Historic Data Filter section to specify the type of retrieved data that Geo SCADA Expert is to store historically for a particular analog point:
- State Change—Select this check box for Geo SCADA Expert to store point state changes historically. Point state changes are stored historically in addition to current data values.
Clear the check box if you do not require Geo SCADA Expert to store point state changes historically. Geo SCADA Expert will then only store current value changes historically.
For example, you may wish to clear the State Change check box if Persistence is being used (see Use Persistence to Stop Fleeting Changes in Value from Changing the Point State) and the point data is to be displayed as a Historic Trend. By storing only current values historically, Geo SCADA Expert will use any Persistence settings for alarm processing, but will only store current data values historically. As a result, Geo SCADA Expert will only display those current values on any Historic Trends for the point.
If you had enabled historic storage of State Changes, two entries would have been stored in the Event Journal whenever a state change occurred—one entry for when the current value changed and another entry when the persistence time had elapsed and a state change occurred.)