data acquisition toolbox with National Instruments Devices: inputSingleScan using USB-6009 vs PCI?

Hello,

I'm using the Data Acquisition Toolbox to read values from a National Instruments Card (USB-6009). I use the inputSingleScan function in a looped manner, which takes samples from the card for each iteration of the loop.

Currently the loop that I use operates at approximately 40Hz. By using the profiler tool, it is clear that the bulk of the time during each loop is used up by the scan function and the associated DAQMX drivers.

I am curious to know what would happen if I switched to a PCI card that was directly plugged in to the computer. Would the inputSingleScan function work faster that way or would it work the same? Is time used because of the nature of the function itself irrespective of the hardware or because I use a USB connection?

Thank you very much.

Answer 1

[Andrei]

The device form factor (USB or PCIe/PCI) will have an effect on the number of single scan iterations that can be achieved per second. USB devices have a higher latency than PCIe/PCI devices.

The MATLAB release you are using is also a factor. Execution time of single scan operations (inputSingleScan and outputSingleScan) has been improved in R2018b ( https://www.mathworks.com/help/daq/release-notes.html )

[Konstantin Bakhurin]

Very helpful, thank you.