Is it possible to stream 60MB to disk at a samplerate of 1MS/s using a NI5112-scope

[Roger_C]

I know you can use the 16 MB buffer on the card and stream (during acquisition) the contents of this buffer to disk. But is it possible to use this buffer as a circular buffer and stream the contents of this buffer to the RAM-memory of the host-pc. Or is the memory on the card the limit. My application requires a high sample-rate (1 MS/s) in combination with a long measure-time (at least 60 s.)

[Leonard]

Hi Buster,

NI-Scope 2.0 allows you to run the 5112 in a continuous mode and includes examples to show you how to do this. This version is posted at http://digital.ni.com/softlib.nsf/current

We ran some benchmarks here and found that on a 333MHz PXI-8156B controller, that we could stream to disk up to 2.32 MS/s on 1 channel of the 5112. With 2 channels, we could stream to disk at 1.11 MS/s. These rates were found using LabVIEW 6.0.

We also tested a 1 GHz Pentium III desktop with MXI III to the PXI chassis and found that we could stream to disk at 12.5 MS/s on 1 channel and 5.88 MS/s on 2 channels. This was with LabVIEW 6.0.

The rates with C were faster.

So the answer to your question is yes. You should be able to run at 1 MS/s with NI-Scope 2.0.

Please
keep in mind that this numbers are only benchmarks and that they will vary from computer to computer depending on what things are installed and running on the machine and what kind of machine it is. We are not guaranteeing that you can run at these rates but letting you know that we have achieved them on computers here.

Best Regards,
Brian

[Roger_C]

Hi Brian,

Do you have any idee if these performance-values are feasible with the PCI-version of the NI5112-scope? Do you use a secondary (RAM-memory) buffer?

Best Regards,
Roger

[Leonard]

Hi Roger,

The numbers I sent you are feasible with the PXI and PCI versions of the 5112.

I am not sure what you mean by RAM-memory buffer. The board (5112) has memory on it and data acquired is stored in this. It is then transferred to the computer and how much is set in the software and can be any number you wish. There is an example in NI-Scope 2.0 that shows a continuous acquisition and you specify in that example how many points to fetch at a time from the hardware.

There is a software user manual that installs with NI-Scope 2.0 that explains how continuous acquisition works with the 5112. You may want to take a look at this and can get it by downloading NI-Scope 2.0 from http://digital.ni.com/softlib.nsf/current.

Best Regards,
B
rian

[KKenM]

Hi Roger,
In High speed acquisation, it is better to move the data to memory ( RAM-memory ->memory space equal to the total amount of data to be collected; reserved before acquisation). Once the acq. cycle is completed, then save data to disk. Ihave used this method with sampling rates >100Mhz and I have not experienced any losses
regards,
Km

[LIM 448]

Hi KMbor,

Your method is exactly what I want? Could you please explain how to hold the data in system memory and then save it to disk afterwards? Did you make your own LabVIEW VI?
I am trying to aquire data for 3 seconds at 30MHz sampling rate with NI-5112 digitizer (32MB on board memory) and my coumputer ram is 256MB.
Thank you, Have a nice holiday!