Hi Phaysal,
There are two memory options on the 5142--are you sure that you are on the 256 MB/ch and not the 64 MB/ch?
The 256 MB/ch should give over two seconds of data if you are using 8-bit data width. If you are on the 64 MB/ch option this would be less than one second.
In either case, using the example code that Jim posted is still only going to allow you to fetch up to what is on the on-board memory. Another idea to try is to fetch the data off of the on-board memory as it is being acquired. You should be able to pull about 80-90 MB/sec of data off of the Scope's memory over the PCI bus. However, standard hard drives typically cannot keep up with this amount of data.
I would look at the niScope EX Fetch Forever shipping example (Help >> Find Examples... >> Hardware Input and Output >> Modular Instruments >> NI-SCOPE >> niScope EX Fetch Forever.vi). This shows how to fetch pre-trigger samples off of the Scope as they are coming in so that data does not get overwritten. You will certainly run into issues if acquiring at 200 MB/sec (16-bit data width), and will likely run into issues even at 100 MB/sec after a certain amount of time.
What do you need to do with all of this data? Are you writing to a RAID 0 array? If you want to stream higher amounts of data continuously the RAID array will be necessary and you should probably also consider moving to a PCIe based platform such as our PXIe-5122.
If you are only interested in a certain frequency band, you could likely use the Digital Downconversion on the OSP of the 5142 to your advantage to reduce the amount of data needed to transfer to your PC.
Best Regards,
John Passiak
