Chapter 7
Counters
©
National Instruments
7-27
X Series User Manual
The co
u
nter stops co
u
nting
u
pon receiving an active edge on the Gate inp
u
t.
The co
u
nter stores the co
u
nt in the FIFO.
Yo
u
can config
u
re the rising or falling edge of the A
u
x inp
u
t to be the active
edge. Yo
u
can config
u
re the rising or falling edge of the Gate inp
u
t to be
the active edge.
Use this type of meas
u
rement to co
u
nt events or meas
u
re the time that
occ
u
rs between edges on two signals. This type of meas
u
rement is
sometimes referred to as start/stop trigger meas
u
rement, second gate
meas
u
rement, or A-to-B meas
u
rement.
Refer to the following sections for more information abo
u
t the X Series
edge-separation meas
u
rement options:
•
Single Two-Signal Edge-Separation Measurement
•
Implicit Buffered Two-Signal Edge-Separation Measurement
•
Sample Clocked Buffered Two-Signal Separation Measurement
•
Hardware-Timed Single Point Two-Signal Separation Measurement
Single Two-Signal Edge-Separation Measurement
With single two-signal edge-separation meas
u
rement, the co
u
nter co
u
nts
the n
u
mber of rising (or falling) edges on the So
u
rce inp
u
t occ
u
rring
between an active edge of the Gate signal and an active edge of the A
u
x
signal. The co
u
nter then stores the co
u
nt in the FIFO and ignores other
edges on its inp
u
ts. Software then reads the stored co
u
nt.
Fig
u
re 7-24 shows an example of a single two-signal edge-separation
meas
u
rement.
Figure 7-24.
Single Two-Signal Edge-Separation Measurement
AUX
Co
u
nter
Armed
8
0 0 0 0 1 2
3
4 5 6 7 8 8 8
Me
asu
red Interv
a
l
GATE
S
OURCE
Co
u
nter V
a
l
u
e
L
a
tched V
a
l
u
e
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