LeCroy SDA, Operator'S Manual

Page: 94 / 397

Logic Trigger
How Logic Trigger Works
Logic Trigger enables triggering on a logical combination of up to five inputs: CH 1, CH 2, CH 3,
CH 4, and EXT. The combination of inputs is referred to as a pattern. There are four logic gates
available: AND, NAND, OR, NOR.
A trigger state is either high or low: high when a trigger source is greater than the trigger level
(threshold) and low when less than it. For example, an AND pattern could be defined as true
when the trigger state for CH 1 is high, CH 2 is low, and EXT is irrelevant (X or don't care). If any
one of these conditions is not met, the pattern state is considered false. You can set holdoff limits
from 2 ns to 20 s or from 1 to 1,000,000,000 events.
Logic Applications
Logic Trigger can be used in digital design for the testing of complex logic inputs or data transmission buses.
Logic Trigger Setup
1. In the menu bar, touch Trigger , then Trigger Setup... in the drop-down menu.
2. Touch the Logic trigger button.
3. Touch the Pattern tab.
4. For each input you want to include in the logic pattern, touch inside the
State data entry field
and select a logic state: Low or High. Select Don't Care for all other inputs.
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