Why is streaming data to disk necessary?

[Alv]

Does streaming data to disk actually take the burden off the buffer to allow the processing of data after its been acquired? I've seen an example or 2 but unclear to the purpose. Can anyone explain?

[Sean_C.]

Hello Alv,

Thank you for contacting National Instruments.

Streaming to disk does reduce the load on the CPU by writing directly to disk instead of building the acquired data into an array. It is an efficient way to log data as it is being acquired rather than waiting for an acquisition to complete, then writing to file.

Sincerely,

Sean C.
Applications Engineer
National Instruments

[Alv]

Is this the most efficient way to acquire multi-channels of data? If so is there a good example where this is done? Most of the examples I ever see are single channel examples. Multiple channels can become complex or seem to be especially to a new user like myself.

[Sean_C.]

Hello Alv,

This is the most efficient way to log data, single or multiple channels.

I have attached an example that acquires and logs analog data. To run this VI, click on the Physical Channels control and select browse. Then select the channel(s) you would like to log.

Let me know if you have further questions.

[coreyGN]

I'm trying to find the most efficient way to write 3 channels to a file. It looks like "Simple Data Logger" is writing in ASCII format, but I thought that Binary is more efficient? Is using the datalogging vi just as efficient as the binary writing vi or even the "Write Characters to File" vi?

[Jeremy_L]

Hi,

There's another example called High Speed Data Logger.vi that comes shipped with LabVIEW. This is a more efficient datalogging example than simple data logger.vi. The major difference between the two is that Simple data logger continuously opens and closes the file reference in the while loop and writes in ASCII. High speed data logger.vi only opens the file reference once, and then continuously writes binary data to the file until you tell it to stop. After it stops, it then closes the reference. This is how to efficiently do it without incurring any excess overhead. Hope this helps!

PS - You can find the example in the NI Example Finder. Go to Help >> Find Examples, and then go to the Search Tab and enter "data
logging" as the keyword.

Jeremy L.
National Instruments

[Jeremy_L]

Hi,

There's another example called High Speed Data Logger.vi that comes shipped with LabVIEW. This is a more efficient datalogging example than simple data logger.vi. The major difference between the two is that Simple data logger continuously opens and closes the file reference in the while loop and writes in ASCII. High speed data logger.vi only opens the file reference once, and then continuously writes binary data to the file until you tell it to stop. After it stops, it then closes the reference. This is how to efficiently do it without incurring any excess overhead. Hope this helps!

PS - You can find the example in the NI Example Finder. Go to Help >> Find Examples, and then go to the Search Tab and enter "data
logging" as the keyword.

Jeremy L.
National Instruments

[Jeremy_L]

Hi,

There's another example called High Speed Data Logger.vi that comes shipped with LabVIEW. This is a more efficient datalogging example than simple data logger.vi. The major difference between the two is that Simple data logger continuously opens and closes the file reference in the while loop and writes in ASCII. High speed data logger.vi only opens the file reference once, and then continuously writes binary data to the file until you tell it to stop. After it stops, it then closes the reference. This is how to efficiently do it without incurring any excess overhead. Hope this helps!

PS - You can find the example in the NI Example Finder. Go to Help >> Find Examples, and then go to the Search Tab and enter "data
logging" as the keyword.

Jeremy L.
National Instruments

[Jeremy_L]

Hi,

There's another example called High Speed Data Logger.vi that comes shipped with LabVIEW. This is a more efficient datalogging example than simple data logger.vi. The major difference between the two is that Simple data logger continuously opens and closes the file reference in the while loop and writes in ASCII. High speed data logger.vi only opens the file reference once, and then continuously writes binary data to the file until you tell it to stop. After it stops, it then closes the reference. This is how to efficiently do it without incurring any excess overhead. Hope this helps!

PS - You can find the example in the NI Example Finder. Go to Help >> Find Examples, and then go to the Search Tab and enter "data
logging" as the keyword.

Jeremy L.
National Instruments

[Jeremy_L]

Hi,

There's another example called High Speed Data Logger.vi that comes shipped with LabVIEW. This is a more efficient datalogging example than simple data logger.vi. The major difference between the two is that Simple data logger continuously opens and closes the file reference in the while loop and writes in ASCII. High speed data logger.vi only opens the file reference once, and then continuously writes binary data to the file until you tell it to stop. After it stops, it then closes the reference. This is how to efficiently do it without incurring any excess overhead. Hope this helps!

PS - You can find the example in the NI Example Finder. Go to Help >> Find Examples, and then go to the Search Tab and enter "data
logging" as the keyword.

Jeremy L.
National Instruments