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

[Nyamekye514]

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. I assume that it is the successive calls cause 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?

Any information would be useful.

Thanks!

[cafedelao]

Hello, Nyamaekye,

I checked the NI USB-6009 User Guide and the maximum AI sample rate is 48 kS/s. According to this, you can use the sample rate you mentioned. Analog inputs and outputs are independent processes, so there shouldn't be a hardware limitation. What could be happening is a limitation when implementing the software, because the hardware does allow it.

You can verify this with community examples (I'm linking some below):

How to acquire and generate data using NI DAQ simultaneously on a continuous basis

https://www.mathworks.com/matlabcentral/answers/153322-how-to-acquire-and-generate-data-using-ni-daq...

Acquire Data Using NI Devices

https://www.mathworks.com/help/daq/examples/acquire-data-using-ni-devices.html