Tektronix CSA7404B, User Manual

Page: 148 / 438

Triggering
3- 80
CSA7000B Series & TDS7000B Series Instruments User Manual
Table 3- 5: Pattern and state logic
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.
State Trigger.
A state trigger occurs when the logic inputs to the logic function
cause the function to be TRUE (or at your option FALSE) at the time the clock
input changes state. When you use a state trigger, you define:
H
The precondition for each logic input, channels 1, 2, and 3
H
The direction of the state change for the clock input, channel 4
H
The Boolean logic function — select from clocked AND, NAND, OR, and
NOR
H
The condition for triggering — whether the trigger occurs when the Boolean
function becomes TRUE (logic high) or FALSE (logic low)
The state (and pattern) logic choices are summarized in Table 3--5.
Setup/Hold Trigger. A setup/hold trigger occurs when a logic input changes state
inside of the setup and hold times relative to the clock. When you use setup/hold
triggering, you define:
H
The channel containing the logic input (the data source) and the channel
containing the clock (the clock source)