Contents - Index


Positioning a trace

 

The position of the chart window relative to a trace is determined by the trace's Offset value.

 

 

Offset and the Chart window

 

The offset for a trace specifies the value of the chart's centerline relative to a trace, and determines the position of the chart window relative to the trace.

 

An offset value close the current value for the trace means the trace will appear close to the center of the chart.  Increasing the offset moves the trace down on the chart, while decreasing the offset moves the trace up.

 

The easiest way to picture this is to think of the trace itself as fixed on some background, and the chart as a window that lets you see a portion of the background.  Increasing the offset moves the window up, causing the trace itself to appear closer to the bottom of the window.  Decreasing the offset has the opposite effect.

 

 

Setting the Offset

 

Before you change the offset for a trace, be sure the trace you want to change it for is the one with the focus.

 

The offset for a trace can be changed using any of several methods depending upon the end result you are looking for:

 

Right-click: Point to where you want the trace to appear:

 

The goal of a single right-click is to move the chart window relative to a trace such that the trace is visible within the chart window and its position relative to the center line is where you clicked.  This is done by taking the last known value for the trace at the time you clicked, and the yDiv setting at the time, and computing a new offset that places that value at the location on the chart where you clicked.  Of course, if the value of the trace is changing, and the yDiv setting is small compared to the changes, then you still may see only a small piece of the trace where it passed through the point now visible on the chart.

 

 

Adjusting the position of the trace: Clicking on the up [^] and down [v] Offset buttons:

 

This method adjusts the window's offset by the current yDiv value each time you click.  The effect is to change the window position as needed to cause the position of the trace within the window to move up or down by one division.

 

 

Set the value for the centerline: Manually entering a value in the Offset text box:

 

The primary use for this method is to set the offset to a specific value to make it easy to compare actual readings to some specific value.  And changing it for multiple traces can make it easier to compare the differences between traces.

 

NOTE:  Depending upon the current yDiv setting, and the current value for the trace, the trace may or not be visible within the chart window after you change its Offset.

 

 

Changing the scaling (yDiv) without moving the trace: Left-click and Smart Offset mode:

 

Sometimes you want to increase or decrease the scaling (yDiv) for a trace, but keep the trace's position in the chart window the same.  As this requires changing both the yDiv and the Offset values at the same time, a special Smart Offset mode was added to make this simpler.

 

The Smart Offset mode is used as follows:

 

NOTES: