Save Data

[M.Ali]

Hi all,

Actually I am saving data to measurement file, the sampling rate is 10K and the sample per chanel is 1000, I am using 4 chanels, at last to save this data I need about 7.8 GB per hour , which is too much.

My question: Can I manage the measurement file to open new file and save data of 10 minutes every one hour, so that I will have data of size 1.3 GB.

Here I attached simle VI to play with, because DAQ board may be not available for all of you.

Thanks .

[mikeporter]

I assume the VI you attached isn't working as you like. What is the problem with it?

With the data rate and volume you are talking about you need to be looking at TDMS.

Mike...

[Bob_Schor]

Do not use Express VIs -- they are extremely limiting, and do not allow you to do things like "start and stop output".  If you separate the task into "Open file for output", "Write N samples", and "Close file", you could easily arrange things so that an inner loop collected a minute's worth of data, wrote it out if it was "minute 1..10 of the hour", and otherwise just discarded the data.  If you have sampling and saving of the data arranged in a Producer/Consumer pattern so you can do both "simultaneously", then you only need to do the deciding on the Consumer (writing) loop.

Another thing to consider is how you save the data.  I'm assuming that your sampling system produces a 16-bit (I16) value for every sample.  By my calculations, an hour's worth of 10KHz samples from 4 channels, two bytes/sample, is 2.3Gb (still big, but not as big).

Bob Schor

[Bob_Schor]

Oops, I got bits and bytes mixed up.  10KHz * 4 channels * 2 bytes/sample * 1 hour = 0.3Gb, much better ...

Bob Schor

[M.Ali]

Thanks Mike and Bob Schor for response.

I think something like this will solve the problem...