Data loss using DAQ USB-6361

[Aliom]

Hello, I would like to measure an analogue input signal with a sample rate of 150 kHz (sample to read = 15k) with a DAQ USB-6361. Therefore, I use the attached LabView programm which basically only contains the DAQ-assistent- and the Write-to-measurement-file-block.

Now, my problem is that my output file shows a big data loss, i.e., data packages of about 100 ms length are followed by data pauses of about 50 ms duration. I only get a continuous digital output signal if I reduce the sample rate to a few hundred Hz (which is way too small for my application).

So my question is: How can I get a continuous data output with a sample rate of 150 kHz? Is it possible to change buffer settings with the help of the LabView DAQ-assistant tool? Or is there maybe something wrong with my LabView program?

[Albert.Geven]

your last guess is probably correct. You should use two parallel loops. One for data collection. One for data saving. They can communicate with the help of an action engine described long ago by Ben Rainer.

[crossrulz]

You really should look at the Producer/Consumer.  The basic idea is that you have one loop reading the data from the DAQ and then another loop to save the data.  The data is sent from the DAQ loop (producer) to the logging loop (consumer) via a queue.

Another alternative is to have DAQmx stream the data straight to a TDMS file.  There is a tab in the DAQ Assistant for logging.  Just enable the logging and the file will be written for you.

[Aliom]

Thanks for your answers and the keywords. I tried the logging-option of the DAQ-assistant and the queue idea but unfortunately I only got data files with unsufficient time resolution for my application. So I will do some research on these action engines...

Have a nice weekend