How to handle large data while acquisition? BNC 2110

Question

I want to acquire data using  BNC 2110, I am writing a software in VB 6. We will use 3 channels. We are supposed to scan about 10000 points before AcquiredData is triggered. in all we will need to scan 10000 * 1000 * 1000 before data is put into a binary fall. Can anybody let me know, how to hande this large number points

Answer 1

Hello Vjuno,
In order to acquire 10,000,000,000 points you are going to have to be streaming this data to your hard drive as you go.  To do this you'll need to write the data you read to a file each loop iteration.  In general it is a good practice to make your "samples to read" at least 10% of your sample rate in seconds to avoid overflowing buffers, however, depending on your computer you may be able to go faster.  I made an example program in LabVIEW and was able to read 10,000 points at a time from each of 3 analog inputs at 333MHz and write the values to file without overflowing a buffer.  However, even opening a web browser while the code was running was enough to delay the VI long enough for the buffer to overflow.
You can use the DAQmx Configure Input Buffer call to increase the buffer size and account for spikes in CPU usage from other processes, and you should also monitor the "Available Samples Per Channel" property to make sure you aren't steadily gaining samples in your buffer.  Since you want to acquire 10 billion samples at 1MHz this acquisition will take several hours; if you're not able to keep the buffer empty then it will become apparent before the end of your acquisition.  By monitoring the samples in the buffer you can tell if you're pulling the samples out fast enough, if you find that this number is steadily increasing then you should either reduce the sample rate or increase the number of samples to read each time you call the DAQmx Read.
In my example program I used a write to TDMS (binary) file and a PCI-6251.
I hope this helps, and have a good night.
Cheers,
Brooks