# Adding a Mask Test

1. From the main menu, choose Measure > Mask Test....

   (If a mask test has already been added, and the mask test results panel is visible, you can also click Add Mask... in the results panel.)

2. Select the signal the mask test will be performed on. This can be a real-time eye diagram or an ordinary waveform.

   When you select an ordinary waveform, the waveform display will automatically switch to Gray Scale persistence. You can also use Color Grade persistence. See Mask Test Requires Color Grade or Gray Scale Persistence.

3. In the Open Mask File browser dialog box, select the mask to use. Mask files use the filename extension .mskx.

   You can select one of the provided mask files (see Provided Standard Masks) or you can select a mask file you have created (see Creating Masks).

   Provided mask files are located in the `C:\Program Files\Keysight\Infiniium\Demo\Masks\` folder. Shortcuts to the provided mask files appear in the default location for user files, `My Documents\Keysight\Infiniium`.

4. Click Open to load the selected mask.

   When the mask is loaded, the following automatically occurs:

   1. If a waveform is visible, the mask appears on the display.
   2. Alignment is allowed, but may be on or off depending on the current setup.
   3. Mask testing begins.

After the mask is loaded, you can change the waveform's vertical or horizontal scale or position without affecting the mask. The mask tracks the waveform as the waveform's parameters are modified.

Results are shown in the Mask Test results panel.See Mask Test Results Panel.

You can change the mask test setup (that is, specify the mask test scaling, margins, and limits). See Changing the Mask Test Setup.

When you are finished testing, you can exit the mask test. See Exit Mask Test.

After a mask is loaded, it remains loaded until you perform a default setup or load a different mask. This feature allows you to load a mask only one time if testing multiple devices against the same mask.

Any change to the waveform setup resets the measurement database and starts the acquisition of new data. The mask test also stops and restarts with the waveform and mask hits counts reset to zero. Changing a channel's vertical scale, vertical offset, horizontal position, horizontal scale, and filter status (on or off), trigger settings, or performing an Auto Scale will also reset the measurement database.