Tektronix TDS5000B Series, Online Help Manual

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When you select Less Than and specify a time, the input
conditions must drive the logic function True for less than
the specified time. Conversely, the True for More Than item
requires the Boolean function to be True for longer than the
time you specify.
The instrument determines the trigger point in the following
manner:
ƒ
It waits for the logic condition to become True.
ƒ
It starts timing and waits for the logic function to
become False.
ƒ
It compares the times and, if the time True is longer
(More Than Time) or shorter (Less Than Time), then it
triggers a waveform display at the point the logic
condition became False. This time can be, and usually
is, different from the time set.
Triggering on Logic State
Use this procedure to trigger the instrument when all of the logic inputs to the selected logic function cause
the function to be True or False when the clock (channel 4) input changes state. (The clock input is channel
2 on 2-channel instruments.)
Select state triggering
1. Push the front-panel ADVANCED button.
2. On the Trigger Setup control window, select the A Event
tab.
3. Click State.
Define state inputs
4. Select an input value from the drop-down list for each
channel. Channels 1, 2, and 3 represent the data inputs on 4-
channel instruments, Channel 1 on 2-channel instruments.
Channel 4 should be connected to the clock signal on 4-
channel instruments, Channel 2 on 2-channel instruments.
5. Select either the Pos (rising) or Neg (falling) edge of the
Clock Channel.
The channel inputs combine to form a logic pattern. Each channel
can have a value of high (H), low (L), or "don't care" (X). A value
is considered high if the channel input voltage is greater than the
specified threshold voltage; a value is considered low if the
channel input voltage is less than the specified threshold voltage.
Use the "don't care" selection for any channels that will not be
used as part of the pattern.