Triggering on Waveforms
TDS 684A, TDS 744A, & TDS 784A User Manual 3–81
edge trigger and certain classes of main pulse triggers. This subsection describes
how to delay the acquisition of waveforms. (The Delayed time base is not
available in InstaVu mode (TDS 700A models only); see Incompatible Modes on
page 3–45.)
There are two different ways to delay the acquisition of waveforms: delayed runs
after main and delayed triggerable. Only delayed triggerable uses the delayed
trigger system. Delayed runs after main looks for a main trigger, then waits a
user-defined time, and then starts acquiring. (See Figure 3–47.)
Wait User-specified
Time Acquire
Data
Wait for
Main
Trigger
Figure 3–47: Delayed Runs After Main
Delayed triggerable looks for a main trigger and then, depending on the type of
delayed trigger selected, makes one of the three types of delayed triggerable mode
acquisitions: After Time, After Events, or After Events/Time. Study Figure 3–48 to
understand the sequence the oscilloscope goes through for each delayed mode.
Wait for
Main
Trigger
Delayed Triggerable
After Time
Wait for
Delayed
Trigger
Event
Acquire
Data
Wait the
User-specified
Number of Delayed
Trigger Events
Wait User-specified
Time
Wait
User-specified
Time
Wait the
User-specified
Number of Delayed
Trigger Events
Delayed Triggerable
After Events
Delayed Triggerable
After Events/Time
Figure 3–48: Delayed Triggerable
The oscilloscope is always acquiring samples to fill the pretrigger part of the
waveform record. When and if delay criteria are met, it takes enough posttrigger
samples to complete the delayed waveform record and then displays it. Refer to
Figure 3–49 for a more detailed look at how delayed records are placed in time
relative to the main trigger.