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5 - 42 FUNCTION REFERENCE
LOGIC TRIGGER (4 CHANNELS MODELS ONLY)
Description:
Logic triggering enables triggering on a combination of the four input signals.
Each input is compared with a trigger level and is recognized as being either
HIGHer or LOWer than the trigger level. The four input signals together can be
regarded to be a 4-bit digital ‘word’. If this ‘word’ matches a certain pattern
triggering occurs. The 4-bit trigger pattern can be edited with the TRIG buttons in
each of the channel sections and is displayed in the lower right hand corner of the
screen with each input being identified as H=High, L=Low, or X=Don’t care.
(Example: HHxL).
There are three logic trigger modes: pattern, state, and glitch.
To enter the logic trigger mode select ‘logic’ from the TRIGGER MAIN TB menu.
The menu now displays the choices, and you use a softkey to select one of the
three logic trigger modes: pattern, state, or glitch.
- State
State triggering, sometimes called conditional triggering, is used in applications
with clocked or synchronous systems. One of the four input signals must be
selected as the ‘clock’ signal. Triggering occurs on this clock edge, when the other
3-inputs match the selected three bit pattern (i.e., are TRUE). The clock edge may
be chosen as a rising or falling clock edge. In this menu you use a softkey pair to
select the trigger slope in combination with the keys TRIG1 through TRIG4 that
give the state (HIGH, LOW, or don’t care) for the three other trigger sources.
Example of a STATE trigger word: HLL, in which ch1 is used as positive clock
edge.
- Pattern
The PATTERN mode is used to trigger the oscilloscope when a combination of up
to four signals is true for a specified amount of time. In other words, triggering
occurs only when two conditions are met; the combination and the time limits.
The trigger pattern is set as a combination of HIGH, LOW, or don’t care, of the
four input channels of the oscilloscope.
Example of a PATTERN: HHxL.
The PATTERN condition is set or edited with the TRIG buttons in each of the
vertical channel sections.
When the PATTERN condition is true for a specified amount of time, the
oscilloscope triggers.