Instrument Control (GPIB, Serial, VISA, IVI)

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My LV program slowsdown after running for several hours

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Hello,

Could you please help me in my problem explained below.

 

My experiments demand to run the LV program for 2- 3 days in a stretch to collect the data @ 10Hz speed using a triggering setup. But after running for few hours, the program slows down and does not aquire the data with the same speed. If I restart the program again, it works fine with required speed.

 

I have LV v4.0.1 running in my Windows 2000 OS. I have PCI-GPIB card connected to Lecroy 8901 GPIB interface for data aquisition. I also have LAB-PC+ to control some motors.

I have NI-DAQ 6.6, NI-VISA for windows 95/NT installed in my system.

 

I thought the problem could be my low end computer and recently upgraded with relatavely high speed mother board and RAM. But the problem is still there.

 

I attached my program file with this message.

any valueble suggestions are greatly apprecited.

 

Thank you.

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Solution
Accepted by topic author fighter

You are building up data to display and this makes your system slow.

Keep your display smaller  and write early data to disk.

greetings from the Netherlands
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Thank you very much Albert Geven for the so quick response.

Now I understood what the problem is.

 

and one more thing, after some stage of my experiment, even though aquisition is @10Hz speed which is controlled by external laser pulse triggering, I only consider three data points for every two hours which are meaningful for further analysis. Rest of the data is just NULL. As I need to keep track of whole data from the beginning, I cant display part of the data. So, if I can exclude the Null data ( which is major part of the data), it shoud make it better.

 

I am sorry to say that, I have very limited knowledge about the LV programming.

Is there anyway I can exclude these Null data from either displaying or writing on to the disc.

 

Thank you once again.

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Hey fighter,

 

A possible solution could be grabbing only the index of your array that you are wanting.  This would allow you to grab a few programmatically controlled data points from your data to be displayed.  You would need to build a new "waveform array" from the parsed data, but for a more detailed solution you may want to search or post on the LabVIEW threads available here.

 

Have a good day!

Message Edited by David P. on 12-17-2008 10:24 AM
David Pratt
Group Manager for Application Engineering Specialists | Automated Test
NIC
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Hi

the best way is to NOT add the null data to the array.

Make a case statement (case structure in LV) with the input connected to a compare with NULL and in the flase case the built (add to array) and in the true case a simple connection.

In reality you have to put also the averaging into the case but you can understand what I mean.

Also my compare with zero is maybe not what you want and I'm ignoring all the other channels.

greetings from the Netherlands
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