Triggering concepts
Overview
User-defined trigger conditions are used to capture waveforms for measurement and analysis. This instrument has simple edge triggers as
well as a variety of advanced triggers.
The trigger event
The trigger event establishes the time-zero point in the waveform record. All waveform record data are located in time with respect to that
point. The instrument continuously acquires and retains enough sample points to fill the pre-trigger portion of the waveform record (that
part of the waveform that is displayed before, or to the left of, the triggering event on screen).
When a trigger event occurs, the instrument starts acquiring samples to build the post-trigger portion of the waveform record (displayed
after, or to the right of, the trigger event). Once a trigger is recognized, the instrument will not accept another trigger until the acquisition is
complete and the holdoff time has expired.
Trigger sources
The trigger source provides the signal that triggers acquisition.
Use a trigger source that is synchronized with the signal that you are acquiring and displaying.
You can derive your trigger from the following sources:
• Input channels. Analog input channels are the most commonly used trigger sources. You can select any of the input channels. The
channel that you select as a trigger source will function whether it is displayed or not.
• Digital channels. These sources are available if you have the MSO option and a digital probe connected. You can select any
combination of digital channels.
• Bus. This source is used to trigger a parallel bus or a serial bus. You can include any combination of analog or digital channels to build
a parallel bus, or use any channel as a component in a serial bus.
Trigger types
Select a trigger type to synchronize your acquisitions.
The available trigger types include:
Edge. This is the simplest and most commonly used trigger type, used with both analog and digital signals. An edge trigger event occurs
when the trigger source passes through a specified voltage level in the specified direction (rising, falling, or either signal voltage).
Pulse Width. Trigger on pulses that are inside or outside a specified time range. Can trigger on positive or negative pulses.
Timeout. Trigger when no edge transition is detected within a specified time.
Runt. Use Runt trigger to trigger on a pulse amplitude that crosses one threshold but fails to cross a second threshold before recrossing
the first. Can detect positive or negative runts, or only those wider than, less than, greater than, equal to, or not equal to a specified width.
Logic. These are special-purpose triggers that are primarily used with digital logic signals. Logic triggers are available on the main triggers.
Triggering occurs when the selected condition goes true. You can also select triggering when the condition goes false, or time-qualified
triggering.
Setup & Hold. Trigger when a logic input changes state inside the setup and hold times relative to the clock. This type triggers on a setup
and hold violation.
Rise/Fall Time. Trigger on pulse edges that traverse between two thresholds at faster or slower rates than the specified time. The pulse
edges can be positive or negative.
Triggering concepts
3 Series Mixed Domain Oscilloscope Printable Help
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