A runt trigger occurs when both the leading edge and trailing edge of a pulse cross only one of two trigger thresholds you specify and with a polarity you specify, where the polarity is relative to the threshold crossed. The oscilloscope can trigger on pulses of positive, negative, or either polarity.

You can also add time qualification to the runt trigger. A time-qualified runt trigger captures only those runt pulses that, in addition to meeting your vertical threshold criteria, have a width either within or outside a duration range you specify. By default, the runt trigger is not time qualified.

Use the runt trigger to debug digital systems by capturing pulses that could represent metastable logic states.

You can configure the runt trigger parameters in NI‑SCOPE using the Analog Runt Ref Trigger instance of the Configure Trigger (poly) VI. Use NI‑SCOPE properties to time-qualify the runt trigger.

The following figure illustrates runt triggering.

Legend

  1. Runt low threshold
  2. Runt high threshold
  3. Positive runt trigger
  4. Negative runt trigger