Can I use "Write Labview Measurement File express vi" outside the loop that aquires the data?

[sampledout]

Previously I have used the "Write Labview Measurment File Express vi" within the loop that reads the data from th DAQmx cards. I have set the options to No Headers and to append to file. This works well within the application. However we now wish to perform multiple Data Aquisition with the same settings when the user presses a "Next" button. So far I have tried to implement this with a While loop and a case structure around th original Data Aquisition loop with a next button as the condition to execute the loop while true. The Next button value is also used to set the new_file option and the express vi is set up to write to a series of files with appropriate settings.

I beleive (I need someone to confirm this for me please?) that I can use the express vi in this situation and that the complete set of data will be passed to the express vi via the tunnel, However I am a little concerned that the data aquisition will require the PC to have adition memory. Is this likely?

Any help would be greatly appreciated.

[JeffBoettcher]

Hello,

I'm not sure I'm getting things exactly right with your application, but I believe you should be able to use these Express VIs in this way.  I'm not sure if you need a case structure or not, depending on whether or not you want any time between acquisitions, or if pressing Next should stop the current acquisition and immediately start the next.

This simple diagram should achieve roughly what you're trying to do, immediately starting the next acquisition when the Next button is pressed.  If you want some time between them, you may need a case structure around the inner while loop controlled by an additional "Go" button or something.

Good luck!

Jeff

Message Edited by Jeff B on 08-15-2006 08:07 AM

[sampledout]

Jeff, Thanks for the quick response. I probably missed some vital information out. Currently the inner loop, where the data aquistion happens, keeps looping until any of a number of conditions is achieved (e.g. number of loops, or any of five digital signals go true). The data aquired within each inner loop iteration is appended to the labview data file.
The next button will need to take this into account, thats why I figured I needed to add a case and an additional while loop.

[Stuart_R]

Hi there,

Is this now resolved? If not, could you post code for what you are trying to do and I will take a look at it and modify to suit.

Thanks,

Stuart

Message Edited by S R on 08-17-2006 06:30 AM

[sampledout]

It has not been resolved yet. However the code is in excess of 3MB and we have an NI Engineer visiting site in a few days so I will ask him then.

Thank you for looking into this for me.