How to Configure Historical Trending in DataHub WebView

One possible cause of this problem is that there are two ways to bind a point value in WebView. One is the "Value" and one is "VQT". When you bind a point, the little drop-down box gives you the choice of value, timestamp, quality, name, etc. The VQT binding contains value, quality, timestamp and point name all in a single record for each point change. The trend chart uses the timestamp as the X axis value and the value as the Y axis value. It uses the point name as the key to look up a history record.

If you bind the point Value instead of VQT, then there is no timestamp and no point name with the value change. The trend chart uses the current system time (which is never going to be as accurate as the timestamp) for the X axis, and simply has no information about the point name, so it cannot make a historical request. Effectively, a direct Value binding will not display history in the trend chart.

If you change the bindings for the trend pens from point Value to point VQT then historical data should be available in the trend.