"Write to measurement file" in labview doesnt show time instants of the waveform

[Vijay Chand]

Hi I am trying to write my data into a file. I am using the "write to measurement file"  for this purpose. But, the file shows only the magnitudes of the input waveform and not the time instants.

Can someone help me with this.

Thanks

Vijay Chand Ganti

[Nabeloabbasi]

hi

i thnik u uses unbundle by name  option which separate you the signal time and data

i think it will work better if u attach your vi

tc

[Vijay Chand]

Hi

Thanks for ur reply. I tried using the "unbundle by name", but thats only helpful for a cluster of elements.What i need is to

get the time instants of an analog signal (to verify its sampling rate).

I am using the example under NI example finder-->Analog Input R series.

Mine is an FPGA application and so im using the R series. I am anyways attatching the VI which i modified for my use.

[Dennis_Knutson]

You have no time data to write. You simply have a 1D DBL. You don't see any time data in the output from the Write to Spreadsheet do you? I would not have been surprised to see a default dt of 1 but that would have been just as incorrect.

Try converting the 1D data to a waveform datatype with a valid t0 and dt.

[Vijay Chand]

Oh!!! Thank you for pointing out that.

Actually, i am new to Labview. I was previously using TMS28335 with simulink, and so may be i am still in that hangover.

Can you please help me out here.

How can it be just a "data" when its actually an input from an external channel. I am feeding a sinusoid of 5kHz freq and 3V(p-p).

Thats a waveform right!! OR  is it that the "analog input" in the FPGA i/o gives only the magnitude information and not the time information.

I have also tried getting the time stamps from the loop time (using measure tick)! But even that did not work.

Please do help me out here!!

[Vijay Chand]

My actual problem is also listed here.

I am a starter with Labview. So please help me out!

[Dennis_Knutson]

The data type you are usimg now (1D DBL) is just an array of magnitudes. The waveform data type is cluster with a magnitude array, a dt, and a t0. You use the Build Waveform function to create a waveform data type if the function does not return one. I have never used FPGA but it looks like you have a loop rate value that might be used.

[Vijay Chand]

Yep. I am trying the same (using the loop rate).

But this FPGA module platform is too complex. It doesnt process "floating point" data firstly and the time stamps are

also too complex to analyze (may be coz i am new to this platform)!!

Ill wait for someone who has already worked on this, to help me out.

Thank you for your inputs 🙂

[Nabeloabbasi]

hi

try to use data manipulation which is available in programming- numeric tool

in FPGa u will get FXP pint so use fxp to I-16 floating point converter in same tool as i mentioned

that will work

any problem tel me again tc

[Vijay Chand]

Dear Nabeloabbasi

Thanks for your reply. I actually tried the same option before. But can u please give me a small detail as to 

"how does the 'type cast' extract the time information of the waveform".... actually as one of the members (denis) pointed out, the analog in contains only the data and not the time information.

What i need is to extract the analog in data into an excel file.

I am currently trying the "FIFO write and DMA access" options...but i guess they are too complex a solution!!!

Please do help me out by explaining a little detail about using 'type cast' to perform the mentioned action.

Thank You.