Trouble Using USB-6009 w/MATLAB Data Acquisition Toolbox and NI-DAQmx

Hello,

I am currently trying to perform both analog output and analog input using the NI-DAQmx drivers for the MATLAB Data Acquisition Toolbox. However, it seems that it is very slow. We need to be able to output a sine wave, then measure a voltage at a speed of around 100Hz. However, when I use outputSingleScan and then inputSingleScan, the best it seems to do is about 40 Hz.

If I just do the outputSingleScan without the inputSingleScan, it looks like it can achieve 1 kHz. It looks like doing the inputSingleScan is what causes the slowdown. Is this a limitation with the hardware? Or, is it a limitation because we are using MATLAB? Would we be able to achieve the speeds we need with the USB-6009 if we were using C? Or, would it require different hardware?

Unfortunately, I have to use inputSingleScan, because I need to synchronize measurements with another device that is connected through TCP.

Any information would be useful.

Thanks!

[Walter Roberson]

40-ish Hz is not uncommon for asynchronous triggered commands over USB when using USB serial emulation if the drivers are not sending the controller push requests. I do not know whether the USB-600x devices configure as serial emulation, and I do not know if the drivers know to send push requests. The problem tends to be observed more on USB connections to arduino or raspberry pi, as those are serial emulation.

[Cait Battle]

Hi David!

We are having the exact same problem as you! We are looping through code that uses inputSingleScan and outputSingleScan; each iteration takes about 33 Hz; and it looks like the switcing from outputtting to inputting data is causing the delay. Did you ever find a way to speed up your system?

Thanks!