Programming instructions

Chapter 27 Counting Signal Highs and Lows
© National Instruments Corporation 27-9 LabVIEW Data Acquisition Basics Manual
Am9513
Figure 27-12 shows the Count Time-Easy (9513) VI located in
labview\examples\daq\Am9513.llb
. This example uses the Count
Events or Time-Easy VI, which can be found in
Functions»Data
Acquisition»Counter
.
Figure 27-12.
Diagram of Count Time-Easy (9315) VI
This VI initiates the counter to count the number of rising edges of a known
internal timebase at the SOURCE of
counter
. The Count Events or Time
VI takes care of dividing the count by the timebase frequency to determine
the
elapsed time
. The counter continues timing until the
STOP
button is
pressed. You do not need to make any external connections if the
number
of counters to use
menu is set to
one counter (16-bits)
. If you
set the
number of counters to use
menu to
two counters (32-bits)
, you must
externally wire the OUT of
counter
to the SOURCE of
counter+1
. The
length of time that can be counted depends on the maximum count of the
counter(s) and the chosen
timebase
. For example, the 65535 (16-bit) count
of the Am9513 and a timebase of 1 MHz can count time for 65 ms. Using
the 100 Hz timebase and two counters (32-bits), you can count time for over
a year. For a complete description of this example, refer to the information
found in
Windows»Show VI Info…
.