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Virtual Data Source - Start Value Not Set

  • Example:

    Here is a virtual data points with logging disabled:

    As you can see:

    Start Value = 0
    Text Render for value 0 = Ok

    Data Source:


    Data Point:


    Point has been enabled, as well as the data source:


    However, the point shows no data:


    The point value can be manually set, and in that case, the value will be changed.

  • Hi mihairosu,

    The data source is not polling, so it is doing no work and serving only as a data warehouse. I suspect this is why the point has no value.

    I'm not sure I feel strongly one way or the other if it should have that value (at what time, when first enabled?) if the data source isn't polling. The original purpose of the start value is to seed the change type, which doesn't matter if the data source isn't polling. However, it's a really easy change, simply add this to the addDataPoint method in VirtualDataSourceRT

            else if(!vo.isPolling()) {
                VirtualPointLocatorRT locator = dataPoint.getPointLocator();
                dataPoint.updatePointValue(new PointValueTime(locator.getCurrentValue(), Common.timer.currentTimeMillis()));

    So maybe this will be made to work that way if it seems better... After all, the point's validation makes you put it in.

  • Okay, understandable.