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Displaying Channels

Creating a Display

Click Trigger to begin streaming data into the display. The data from each channel defines a unique trace (line). To quickly scale the data, right-click the display and select Autoscale from the menu.

The display area contains this information:

  • Labels and markers for each trace. For this example, the traces are labeled CH0 and CH1.

  • Labels for the vertical units for each trace, and a label for the horizontal units for the display.

When the acquisition is not running, you can display data tips by moving the mouse cursor over the trace. The data tip is indicated by a red circle, and displays the value of the trace at the selected point. If you press the Control key while the cursor is over the trace, the difference between the first data tip and the last data tip is displayed.

Creating Additional Displays

To add additional displays to the Oscilloscope, use the Scope pane of the Scope Editor GUI. To open this GUI, select Scope from the Edit menu. As shown below, the new display is named display2.

To show a trace in a particular display, use the Channel Display pane of the Channel Editor GUI. To open this GUI, select Channel from the Edit menu. As shown below, CH0 is associated with the new display.

The Oscilloscope is now configured so that the CH0 trace is shown in the bottom display, and the CH1 trace is shown in the top display.

Configuring Display Properties

You can change the display characteristics of the Oscilloscope by configuring display properties. You access the display properties these two ways:

  • Property Inspector — Place the mouse cursor in the display of interest, right-click, and select Edit Properties from the menu.

  • Scope Editor GUI — Select Scope from the Edit menu, and then choose the Scope Properties pane.

For this example, use the Scope Editor GUI to change the color of both displays to white. The steps are

  1. Select both displays from the Select the scope components list.

  2. Open the color picker for the Color property.

  3. Select White from the color picker pop-up menu.

The Scope Properties pane and color picker are shown below. For descriptions of all display properties, click the Help button.

Math and Reference Channels

In addition to hardware channels, you can display

  • Reference channels — The data associated with a reference channel is defined from a MATLAB® variable or expression. You should use reference channel data as a known waveform against which other data is compared.

  • Math channels — The data associated with a math channel is calculated in the MATLAB workspace using the data from existing hardware channels, math channels, or reference channels.

You use the Channel pane of the Channel Editor GUI to create math and reference channels. You open this GUI by selecting the Edit > Channel menu item. For example, suppose you want to create a reference waveform to compare to the CH0 waveform. The first step is to create the reference data in the MATLAB workspace:

t = 0:0.0001:0.2;
w = 200*2*pi;
ref = 3.75*sin(w*t);

The next step is to define the reference channel in the Channel Editor GUI. The Channel pane shown below is configured to create a reference channel called r1 using the data defined in the variable ref, and to display the reference channel data with CH0 in display2.

Note that instead of creating the variable ref in the workspace, you can specify the expression 3.75*sin(w*t) in the Expression field.

    Note:   If the expression returns a complex value, only the real part of the value will be displayed.

Defining a math channel is similar to defining a reference channel. The main difference is in specifying the expression. For a reference channel, you specify a MATLAB variable or expression. For a math channel, you specify

  • The channel name — Channel names are given by the Name column in the Defined channels table.

  • A valid MATLAB expression — When the expression is evaluated, the channel names are replaced with the associated data that is currently being displayed.

The Channel pane shown below is configured to create a math channel called m1 using the CH0 and CH1 data, and to display the math channel data with CH1 in display1.

The traces for the hardware, math, and reference channels are shown below.

Removing Channel Displays

You can remove a channel from a display one of these ways:

  • Channel Editor GUI

    • The Channel pane — Clear the associated check box in the first column of the Defined channels table.

    • The Channel Display pane — Select <not displayed> from the Display column of the table.

  • The On/Off button of the Channel Scaling pane. Refer to Channel Data and Properties for more information about this pane.

The Channel pane is shown below with the math and reference channels cleared from the Oscilloscope displays.

Note that if you clear the check boxes, then in addition to the channels not being displayed:

  • For hardware channels, data is not streamed into the Oscilloscope.

  • For math and reference channels, the values are not calculated.

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