Why do i get crashes when setting chart history length 
Author Message
 Why do i get crashes when setting chart history length

I am trying to figure out how to get my chart to eat up less memory.
At the moment it is capturing from 4 channels at 44100 samples/sec. It
is a continuous capture and after a few minutes, the computer just
runs out of memory and can no longer keep up with the capture, at
which point the Vi quits. Opening up task manager, I noticed that as I
capture, the memory gets chewed up really quickly, but when I stop my
VI the used memory is not reclaimed. Even if I set the chart history
to an empty array when the VI stops. I tried setting the chart history
to a smaller number but whenever I set it below 512 the whole computer

Sun, 31 Oct 2004 05:09:31 GMT  
 Why do i get crashes when setting chart history length
LabVIEW acquires memory in chunks and does not necessary return the
memory when the VI is through running.  You can have labview return
the memory as soon as possible if you open LabVIEW  >>  tools >>
options >> performance and disk.

Charts just update one value at a time on the right and push older
data to the left.  This older data is the chart history.  The only way
to minimize the data used by the chart is to minimize the number of
data shown.  I do not think the problem is with the chart history.  We
can check this by removing the chart from your program and running the

You can also run a trial test at a lower sampling rate or on fewer
channels to see if you still run out of memory.  If you still do, I
suspect there is some structure (other than the chart) in your program
that is wasting resources.

How much ram do you have and what version of LabVIEW are you running?

Jeremy Braden
National Instruments

Sun, 31 Oct 2004 22:57:10 GMT  
 Why do i get crashes when setting chart history length
Thanks for the reply. I have tried setting the performance and disk
options to reclaim memory as soon as possible but it doesn't make any
difference. I am pretty sure it is the chart using the memory, because
as soon as I change the chart to a graph, the problem disappears. When
I set the chart history length to anything below about 500, the
machine always crashes. The machine has 128mb ram and is running
Labview v6.0.

Mon, 01 Nov 2004 20:29:59 GMT  
 Why do i get crashes when setting chart history length
What happens when you set the history to 1024 elements? Also will you
get the leak when you run the program with the chart deleted?

I suggest creating an experiment where you simulate your data and
write to the chart.  If you see a leak with this VI, post it.

Jeremy Braden
National Instruments

Wed, 03 Nov 2004 07:35:47 GMT  
 [ 4 post ] 

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