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Pattern Trigger
A pattern trigger occurs when the inputs to the selected logic function cause the function to
become True or False. When you use a pattern trigger, you define:
The precondition for each logic input: logic high, low, or "don't care"; the logic inputs are the
instrument channels
The Boolean logic function: AND, NAND, OR, or NOR
The condition for triggering: the Boolean function becomes True (logic high) or False (logic
low), and whether the True condition is time qualified
Pattern trigger logic choices are summarized in the following table:
Pattern
State
Definition 1, 2
AND
Clocked AND
If all the preconditions selected
for the logic inputs
3
are TRUE,
then the instrument triggers.
NAND
Clocked NAND
If not all of the preconditions
selected for the logic inputs
3
are
TRUE, then the instrument
triggers.
OR
Clocked OR
If any of the preconditions
selected for the logic inputs
3
are
TRUE, then the instrument
triggers.
NOR
Clocked NOR
If none of the preconditions
selected for the logic inputs
3
are
TRUE, then the instrument
triggers.
1
For state triggers, the definition must be met at the time the clock input changes state.
2
The definitions given here are correct for the Goes TRUE setting in the Trigger When menu. If
that menu is set to Goes False, swap the definition for AND with that for NAND and for OR with
NOR for both pattern and state types.
3
The logic inputs are channels 1, 2, 3, and 4 when using Pattern triggers. For State triggers,
channel 4 becomes the clock input, leaving the remaining channels as logic inputs. (On the
TDS5000B 2-channel instruments, channel 2 is the clock input.)
Summary of Contents for TDS5000B Series
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