time stamp with processed data

[labviewmission]

Hi,

I have an application acquiring data continously. The data points are acquired using DAQmx ,then goes into a RT FIFO . From there these data values are being collected in circular buffers.

Then depending upon number of points user selects , the data points are selected from the buffer and averaged. This is then displayed and again written onto circular buffer and it continues.

Then come data logging into picture.

Now I want to log these data points with the 'dt' that the user mentions. I am resampling the samples and getting the desired result. I am logging the data points onto the LVM file.

Now I have 2 new requirements---

a)Get absolute Time Stamp(does not require to be very precise) I have added the time stamp in the comment column. But since I am writing an array of data points from the buffer ,I cannot attach absolute time stamp with each Data Point. Presently I am calculating the same from Time stamp in The Header information and time interval in the LVM file which is not correct.

b)Log "number of points" as selected by the User. When I try to give the number of data points to the Buffer of data points before resampling, the number of data points that I am getting are much lesser than what I want.

All I need is a simple example() of data acquisition and then collecting into buffers and processing it and then being logged with Time Stamp using 'Write to measurement file'.Also resample the data before writing.

I hope I made myself clear.

Please post here for suggestions and doubts.

Any help is greatly appreciated.

Regards

[NathanT]

labviewmission,
       Have you had a chance to browse through the example finder in LabVIEW?  Also, what version of LabVIEW are you using, and on what RT target?  Are you using multiple loops of different priorities?

Thanks,

NathanT

[labviewmission]

Hey Nathan,

I am glad that you replied.

I am trying to target an RTX system.

This code was originally developed by someone else.

I am trying to make it more user friendly and easier to operate.

I have found the problem that I was having. Actually the data was being documented using an event structure and it was writing whatever it was having at that moment of time in the array.

I am using Labview 7.1 but will be upgrading it to Labview 8.0.

I am targeting a RTX system.

I have gone through few examples but each of them is fulfilling the requiremnet independently.

All I want is log continous array of data and each having a time stamp(absolute) of its own, resampled at desired user 'dt'.

Regards

[NathanT]

labviewmission,
      What RT specific operation is your application doing?  Can you define the way that you are using the term "resample"?  Does it mean have a variable sampling rate, or going back through the array of collected data?  The DAQ by itself does not need RTX.

Thanks,

NathanT

[labviewmission]

Nathan,

The RT is to precisely control a parameter by using PID control methodology.

By resampling I mean going back to collected array of data.

I have used the multi-task design example to solve my problem.

I have used another while loop for logging the data at a different rate and no resampling of the collected data is required now.

I am writing data at a different rate from acquisition.

Sorry for not using the correct terminology to describe my problem.

Now its doing exactly what I wanted it to do.

Thanks for your concern

Regards