The buttons in the Historical Data Viewer page's tool bar enable you to manipulate analog data to view lesser scale ranges. For example, instead of viewing a minimum value of "0" and a maximum value of "100" for all pens plotting analog data, you may wish to view a scale range of "-30" to "170".
Note: Unlike the Zoom In X-axis and Zoom Out X-axis buttons, the Zoom In Y-axis (Analogs Only) and Zoom Out Y-axis (Analogs Only) buttons only work with analog values.
1. Ensure that pens plotting data for some or all of the analog tags in your application have been added to the pen legend.
2. Click the currently selected pen in the pen legend(i.e. a selected pen is one with a rectangle displayed around it in the pen legend). The formerly selected pen should now be deselected (i.e. no pens should be selected in the legend).
3. Click the Zoom Out Y-axis (Analogs Only) button.
4. Click on the analogs graph (the top-most graph; the bottom-most graph displays digital values if any pens plotting digital data are present in the pen legend). The scale range for all selected analog pens will adjust to display a greater scale range, as is indicated by the tag's maximum and minimum scale values to the left of the graph.
5. Continue to click on the graph until the scale range for the selected analog has been set as you require.
Note: To reset the scale range for all analog pens, ensure that no pen is selected in the legend, and then click the Reset Y-axis (Analogs Only) button in the tool bar.
The section that follows provides instructions on shifting a selected analog's scale range on the graph.