Transfer rate with USB 5102 is very slow (8 updates/sec). Any possible way to increase it??

Question

Taking 100 microsec data from 32 sensors we want to monitor results in real time. Because of slow data transfer protocol (niScope_InitiateAcquisition - niScope_FetchBinary8 loop) for USB NI5102 (~125ms) we can update only every 4 sec. Any way to speed it up? Is PCMCIA 5102 will do it faster (we don't have PCI)??

Answer 1

To verify, you wish to take data for 100 microseconds on each of 32 sensors and display the data in "real time." The problem is the overhead of the initiate/acquire, not the actual acquisition time or theoretical data transfer time. Have you considered taking all your data in a single acquisition? I assume you are already multiplexing the signal to the 5102. This will require a bit of work in setting up the advance trigger for the multiplexer and the reference trigger for the 5102, but this is far cheaper than buying another acquisition board. Your data acquisition sequence would then be:
Set 5102 for 64000 points, 20MHz, 0% trigger reference position (add more points if needed for settling time)
Set multiplexer to first channel
Iniate acquisition on the USB-5102 (you may want to use the hardware start trigger for repeatability)
Trigger 5102 to start acquisition
Cycle multiplexer through the 32 sensors with 100 microsecond dwell time per sensor (add extra dwell time for settling time as needed)
Read data from 5102
Parse the data by splitting the array using your known timing
With this method, you only take the overhead hit once per scan instead of 32 times. You should be able to get single-digit Hz update rates. You can speed up the data acquisition by using both channels of the 5102 (unless you are already doing this for some sort of data reduction). If you are doing this in LabVIEW, pass your data into a queue in your acquistion loop and pull it out of the queue in a separate loop to process and display. This allows you to time multiplex the acquisition and display.
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