How to adjust the range of time so that the value of the tag is automatically stored?

Dear all ,

Iam working on a project which needs to store a tag value in historical data for 3 months and show it in trend view  . my Problem [snip] how can i adjust the range of time so that the value of the tag is automatically stored when the run time starts and  the oldest data deleted automatically according to FIFO concept ? 

thank you

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Split from WinCC Basic V13 SP1 – Simple Sample: Real Time Trends.