graphing persist

[paulneal]

Hi,

Is it possible to graph using persist data?

Paul.

[AzeoTech]

Certainly. But to access any persist data you MUST subset. Doing just MyChannel will only give you the history. The easiest way to do this is to use the CurrentScaleFrom/ScaleTo variables of the graph:

MyChannel[bottomAxis.CurrentScaleFrom,BottomAxis.CurrentScaleTo]

These variables contain the current X axis scaling, so by using them, you are only retrieving from Persist the data points needed for the graph.

The reason you have to subset persist is to keep you from accidentally loading a huge persist (and persist files can hold millions of data points) into memory when you really only needed 100 points.