Hello! When using KEPServerEX's IDF, the history you see in Splunk is stored only in your Splunk Indexer. Unless you are using our Local Historian or our DataLogger Plugin, KEPServerEX keeps only them most recent value for any data point in its internal cache.
If you're interested in storing data longer-term with KEPServerEX, have a look at our Local Historian and our DataLogger Plugin. NOTE that an OPC HDA Client is required to obtain data from the Local Historian Plugin:
http://www.kepware.com/spec-sheets/local-historian.asp
http://www.kepware.com/Products/OPC_Data_Logger.asp
Hope this helps!
Sam Elsner
Senior Applications Engineer
Kepware Technologies
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