User`s guide

Controlling Logging Parameters
Determining How
Many Frames Are Available
The FramesAcqu i
red
property tells how many frames the object has logged
since it was star
ted, described in “Determining How Much Data Has Been
Logged” on page 5
-23. Once you move frames from the memory buffer
into the MATLAB
workspace, the number of f ram es stored in the memory
buffer will dif
fer from the
FramesAcquired value. To determin e how m any
frames are curr
ently available in the memory buffer, check the value of the
FramesAvaila
ble
property.
Note The Frames
Available
property tells the number of frames in the
memory buffer
, not in the d isk log, if
LoggingMode is configured to 'disk' or
'disk&memory
'
. Because it takes longer to w rite frame s to a disk file than to
memory, the n
umber of frames stored in the disk log might lag behind those
stored in the
memory buffer. To see how many frames are available in the disk
log, look at t
he value of the
DiskLoggerFrameCount property. See “Logging
Image Data t
o Disk” on page 5-40 for m ore information.
This exampl
e illustrates the d istinction between the
FramesAcquired and the
FramesAvai
lable
properties:
1 Create an im
age acquisition object — This example cre ates a video
input objec
t for a Wind ows image acq ui si tion device. To run this example
on your sys
tem, use the
imaqhwinfo function to get the object constructor
for your im
age acquisition device and substitute that syntax for the
following
code.
vid = videoinput('win video',1);
2 Configure
properties — For this example, configure an acquisition of 15
frames.
set(vid,'FramesPerTrigger',15)
3 Start the
image acquisition object —Callthe
start function to start
the image
acquisition object.
start(vid)
5-25