The buttons in the Historical Data Viewer page's tool bar enable you to manipulate analog data to view greater scale ranges. For example, instead of viewing a minimum value of "0" and a maximum value of "100" for a selected analog, you may wish to view a scale range of "-31" to "169".
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 at least one pen plotting data for an analog tag has been added to the pen legend.
2. Select the pen plotting data for the analog tag in the pen legend. A rectangle will appear around the pen to indicate that it is selected.
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 the selected analog pen 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 modifying the scale range for a group of pens plotting analog values.