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B-13
Reference Trigger
Use the Reference Trigger to stop the acquisition. It is normally used in pretrigger acquisitions;
it is necessary to acquire data before and after the trigger. The Reference Trigger signals the time
when the AI timing engine starts counting the number of posttrigger conversions to take before
stopping. The Reference Trigger can come from external or internal sources and its source is
selected with a multiplexer. Its output is called the Selected Reference Trigger.
Figure B-13.
Reference Trigger and the Analog Input Timing Engine
Figure B-14.
Reference Trigger Timing Diagram
S
t
a
rt Trigger
Termin
a
l
S
elected Reference Trigger
Reference Trigger
Termin
a
l
Termin
a
l
S
elected
Sa
mple Clock
Termin
a
l
Termin
a
l
Termin
a
l
S
elected
S
t
a
rt Trigger
RT
S
I
Termin
a
l
Termin
a
l
Termin
a
l
S
elected P
aus
e Trigger
S
I
Co
u
nter
Block
S
I2
Co
u
nter
Block
S
I_TC
Sa
mple Clock Time
bas
e
S
ync
Sa
mple Clock Time
bas
e
Convert Clock Time
bas
e
S
ync Convert Clock Time
bas
e
p_AI_Convert
S
t
a
rt
1
S
I2_TC
S
I
S
t
a
rt
POUT
P
aus
e Trigger
_i
POUT
S
elected Reference Trigger
S
ync Convert Clock Time
bas
e
Reference Trigger
t
22
t
26
t
26
t
25
t
24
t
2
3
