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User Manual 55
Trigger Mode
The oscilloscope’s trigger mode includes Auto, Normal and Single. The Trigger Mode
affects the way in which the oscilloscope searches for the trigger.
After the oscilloscope starts running, the oscilloscope operates by first filling the
pre-trigger buffer. It starts searching for a trigger after the pre-trigger buffer is filled and
continues to flow data through this buffer while it searches for the trigger. While searching
for the trigger, the oscilloscope overflows the pre-trigger buffer and the first data put into
the buffer is first pushed out (First Input First Out, FIFO).
When a trigger is found, the pre- trigger buffer contains the events that occurred just
before the trigger. Then, the oscilloscope fills the post- trigger buffer and displays the
acquisition memory.
Press the Auto , Normal and the Single buttons on the front panel to select the desired
trigger mode, and the corresponding status light will be lit.
➢
In the Auto trigger mode (the default setting), if the specified trigger conditions are
not found, triggers are forced and acquisitions are made so that signal activity is
displayed on the oscilloscope.
The Auto trigger mode is appropriate when:
●
Checking DC signals or signals with unknown levels or activity.
●
When trigger conditions occur often enough that forced triggers are
unnecessary.
➢
In the Normal trigger mode, triggers and acquisitions only occur when the specified
trigger conditions are found. Otherwise, the oscilloscope holds the original waveform
and waits for the next trigger.
The Normal trigger mode is appropriate when:
●
You only want to acquire specific events specified by the trigger settings.
●
Triggering on an infrequent signal from a serial bus (for example, I2C, SPI, CAN,
LIN, etc.) or another signal that arrives in bursts. The Normal trigger mode lets
you stabilize the display by preventing the oscilloscope from auto- triggering.
➢
In the Single trigger mode, the oscilloscope waits for a trigger and displays the
waveform when the trigger condition is met and then stops.
The Single trigger mode is appropriate:
●
To capture single event or a periodic signal.
●
To capture burst or other unusual signals.