Use the channel-based attributes to set the reference levels. The Measurement Library example shows how to set the reference levels. You can customize how NI-SCOPE configures the percentages used for the reference levels with the Percentage Method attribute. This attribute uses any of the following constants:

  • Min Max—This method uses the measurement's voltage minimum and voltage maximum as 0% and 100%. These algorithms find the absolute minimum and maximum in the waveform, which is useful for sine waves and triangle waves where the histogram method does not work.
  • Low High—This method uses the measurement's voltage low and voltage high as 0% and 100%. The voltage low is the voltage of the histogram bin with the most hits below 40% of the waveform's voltage peak-to-peak value. The voltage high is the voltage of the histogram bin with the most hits above 60% of the waveform's voltage peak-to-peak value. These measurements use the last-acquisition histogram method to find the most common high and low voltages, which is useful for ignoring the preshoot and overshoot on a square wave.
  • Base Top—The voltage base and voltage top measurements correspond to 0% and 100% with this method. These measurements use the last-acquisition histogram method if the most common histogram bin contains a substantial number of the total points. Otherwise, it returns the absolute minimum and maximum values in the waveform, which is a useful default value for most waveform types.

You can also configure the reference levels in terms of voltage with the Ref Level Units attribute.