Now that you have created and deployed your first measure, let’s go back to the Data Source tag and compare the detailed values to the measure’s summarized values for each hour.
Select the “Data Sources” tab at the bottom of the Information Model and double-click the “010-TT-001.PV” Boiler Temperature item …
The “Data Source Preview” is a useful view into the detailed data. After opening the “010-TT-001.PV” tag, play with “Zoom In”, “Zoom Out”. Double-click to zoom in. Notice the right-click context menu options for each chart: “Pin to Zero”, and each item: “Format”, “Style”, “Width”, “Move” and “Remove”.
The “Data Source Preview” window has two chart sections, top and bottom. By default the top section is used, however, additional tags, measures and events can be added to these two sections.
Drag the “Steam Temperature (˚C)” measure from the Model View onto the bottom section. By default, the “Pin to Zero” setting is unlocked. Notice how the time axis is always kept in synchronization between the top and the bottom sections. This is useful for alignment and troubleshooting.
Remove the “Steam Temperature (˚C)” item from the bottom section and add it to the top section. You should now see the overlap of the summarized measure values, changing every hour, overlaid on the detailed value. Zoom out to about 8 weeks of data. You should notice that the legend for the detailed values adds the word “Sampled”.
Be aware of “Sampled” because the chart only shows a subset of the detailed data, evenly spaced over the period. This means that some important points may not be shown. As soon as you zoom in enough, and the word “Sampled” disappears, you will know you have all the data points displayed. Note that the grid view will always show all data points.