If your device can send 1 MB/s (8 Mb/s divided by 8 bits per byte), then NI-VISA should have no problem reading that amount if your connection is USB 2.0 all the way through.
We have seen NI-VISA transfer upwards of 25 MB/s on large buffers in a pure USB 2.0 system, and while that may vary by machine and by OS, that's way above the transfer rate you are asking about.
On a system with any USB 1.1 connection (the host, a hub, or the device in question), the transfer rate is of course much lower, as you'd expect based on the USB 1.1 standard. We've seen NI-VISA transfer roughly 1000 kB/s (that's slightly less than the 1 MB/s you need). Again, that may vary slightly if you try it on a different machine or OS.
I hope this information helps.
Dan
Mondrik
National Instruments
