How to perform INFINITE (in time) data acquisition with PCI-6120

[WiGr]

Hello,

I'm using a PCI-6120 data acquisition board which has onboard memory of 64Msamples.

When you program the 'number of samples', this is a FINITE number after which data acquisition stops.

I need longer recording times. So possibly, I need the onboard memory (64Msamples) for implementing a swing buffer.

During one part of the swing buffer is filled with datasamples, the other half is streamed to harddisk.

So I need control of where to put data from the AD-converter into the swing buffer and from which part to read data from.

How can this be achieved? I hope this can still be done in a MATLAB environment, which I use now.

I can image that someone somewhere developed a method for this.

Kind regards,

Wim

[Tom_Powers]

How fast are you streaming the data.  We have done this on PCs using LV at rates kind of like some kS/s. Basically you just read the buffer write it to file then read the buffer . . . 

The only limitation is the Windows file size limit which is something like 1 GB.  

If application is that kind of speed or slower then I will dig up the application and see about wrapping it up in a .llb file and sending it to you.  I think it was done in DAQmx so it with a few tweeks it should just be plug and play.

[WiGr]

Hello Tom,

The sample rate lies between say 40kS/s to 300kS/s depending on the bandwidth to capture which s pretty fast. Furthermore it is not allowed that we miss data due to reading a buffer. So, during reading of the buffer, data acquisition must ongoing.

That's why I don't quite fully understand your sentence "Basically you just read the buffer write it to file then read the buffer . . .".  I think that this is what we did before resulting in FINITE recording times and causing time gaps in the data due to every time restarting of the acquisition. So to me "Basically" looks more complicated.

Kind regards.