Rigol VS5000 Series User Manual page 78

Trigger Key Points
1. Trigger Source:
Trigger occurs from several sources: Input channels (CH1, CH2 and D15-D0 (for
VS5000D only)), AC Line, Ext, Ext/5.
CH1 or CH2: It is the most commonly used trigger source. The channel will work
when selected as a trigger source whatever displayed or not.
Ext Trig: The instrument can be trigged from a third source while acquiring data
from CH1 and CH2. For example, to trigger from an external clock or with a signal
from another part of the test circuit. The Ext, Ext/5 trigger sources use an
external trigger signal connected to the Ext Trig connector. It has a trigger level
range of +1.2 V to -1.2 V. The Ext/5 trigger source attenuates the signal by 5X,
which extends the trigger level range to +6 V to -6 V, allowing the oscilloscope to
trigger on a larger signal.
2. Sweep Mode:
The sweep mode determines how the oscilloscope behaves in the absence of a
trigger event. The oscilloscope provides three trigger modes: Auto, Normal, and
Single.
Auto: This sweep mode allows the oscilloscope to acquire waveforms even
when it does not detect a trigger condition. If no trigger condition occurs while
the oscilloscope is waiting for a specific period (as determined by the time-base
setting), it will force itself to trigger.
When forcing invalid triggers, the oscilloscope cannot synchronize the waveform,
and the waveform seems to roll across the display. If valid triggers occur, the
display becomes stable on the screen.
Any factor results in the un-stability of waveforms can be detected by Auto
Trigger, such as the output of power supply.
NOTE: When horizontal control is set more than 50 ms/div, Auto mode allows the
oscilloscope to capture without trigger signal.
Normal: The Normal mode allows the oscilloscope to acquire a waveform only
when it is triggered. If no trigger occurs, the oscilloscope keeps waiting, and the
previous waveform, if any, will remain on the display.
Single: In Single mode, after pressing the RUN/STOP key, the oscilloscope waits
for trigger. While the trigger occurs, the oscilloscope acquires one waveform and
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User's Guide for VS5000 Series
© 2008 RIGOL Technologies, Inc