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Problems Time Stamping

I am currently haveing a problem timestamping data that is being aquired by the NI USB-6211 DAQ. My problem is that it will record the data and time stamp only the first of each data set. If set to triggered input, it will only record a timestamp at hte start of each triggered input. Anyone have any ideas? Data file and VI attached for anyone interested

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Message 1 of 6
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It has to do with the way you are acquiring the data. A LV waveform has a t0 value (the start time) and deltaT value (the time between samples) and then an array of data points.

 

But if you think about it, that is really all the data you need. Assuming a start time of 2:00:00 and a sample rate of 1kHz the 1000th sample will occur at exactly 2:00:01. Its a simple matter of multiplication.

 

Mike...


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Message 2 of 6
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Thought this is technically correct, is there a way to timestamp every point of data? I would rather not set up a seperate macro/VI to go through and multiply thousands of points of data.

What would be the most elegant solution here?

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Message 3 of 6
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Don't use the Write to Measurement File if you do not like the format. There is Export Waveforms to Spreadsheet File. That writes the absolute time on each line. Otherwise, you can use one of the lower level file write functions. There is the function Get Waveform Time Array that creates the timestamps from the t0 and dt so the separate VI is something you do not have to write.

Message 4 of 6
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This has pointed me in the correct direction. However, in the final VI, we want to include a triggered input. How would I go about doing that? Whenever I try to just impliment Export Waveforms to Spreadsheet file in place of the write to Measurements File, I recieve a error stating "Some or all of the samples requested have not yet been acquired." originating from the DAQ assistant output and any waveforms that I save have no data. Any pointers there?

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Message 5 of 6
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GroveIns

 

How have you configured your DAQ Assistant?

 

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Message 6 of 6
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