History trends


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I wonder if it is possible to show data from ODBC source so that a user could set graph width (time) online from one hour to a week or month. The idea is to compare current process batch to one that was done a month or a year ago. Time setting could done be typing in the date or rewind or fast forward with buttons like in many other SCADA software do.

From the DF manual I get the impression that it is suggested to use some other software for this kind of data handling but I would prefer to have only one application for user to mess with.

Has anyone done this?

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Actually, the manual is referring to analysis, not review. For long term review, using the Channel Persist is the easiest way. Just set the Channel Persist value to something big enough to cover the desired look back time and then make sure and subset your data in your Y Expression (probably by time), and you can review back in history. I believe the QuickModPro sample shows how to do the subsetting using variables in the graph control itself so the subsetting matches the graph scaling.

You can do it through ODBC too, but it requires scripting to load the data back into DAQFactory. Channel persist does it automatically, but like most automatic things, doesn't offer as much flexibility as doing it in script.

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