Write data from DAQ-Assistant only with rate 2 Hz

[hellboy]

Labview diagram contains standard While loop.

I aquire data from DAQ Assistant each with rate N Samples - Samples to read = 100 is and Rate = 1 KHz.

But I need to save data only with rate 2 Hz.

[GrahamG]

Do you mean that you want to save your each piece of data separatly with a rate of two Hz therefore saving it all to a buffe and then taking 50seconds to dave it all or do you mean to save all the data points as an array of 100 points at a rate of two hz.

Both are possible but can you give me a little more information as to what you need.

which version o labVIEW are you using also incase I need to post some example code.

Thanks

best regards

[hellboy]

Data are aquired  with rate 1KHzand shows o screen.

I should write not all aquired data (too much), but only subsamples.

For example:

on screen - with 1KHz

to file - with rate 1 Hz only one value

[GrahamG]

I think the best way of doing this would be to index from the array of data that is coming out of your DAQ assistant one point and write these single points into a new array tha you could then write to file or save.

For example, if you are using N samples aquisition at N = 100 and frequency = 1k you will be reading 0.1s of data at any time. If you place an index array node on the output of your express VI and leave the default index at 0 then you will read back just the first element of each 100 element output. If you were to write these elements o an array or to a file you would be displaying the full 1k data but only saving at 10 Hz.

This same theory with a little ajustment I'm sure could be used to fit your application.

If you would like me to write you some sample code then please post back  

best regards