I'm using MATLAB to read data from the NI USB-6218. I do know for sure that it is reading data correctly. I can read 1000 samples of data in 0.22 seconds. It takes 50.32 seconds to read 5000 data points. For 10,000 it's 126.74 seconds. I'm storing all of these data into one matrix. Is it possible that the device is defective, or is it my code? I also posted a thread on MATLAB's forum asking if it's just the language that's slowing it down. Here's my code: ai = analoginput('nidaq','Dev2'); ai0 = addchannel(ai, 0); ai.SampleRate = 1000; start(ai); pause(.2); for i = 0:1:1000 ai_value = getsample(ai) end % Clean up delete(ai); Again, the code works, and I'm 100% sure it's reading everyting correctly. It just gets slower and slower as more data comes in. Any idea why this is happening? Thanks.

Multifunction DAQ

Author

That's true, I'm understanding that better now... The sample rate is meaningless if I use getsample()

It's the only one my supervisor is satisfied with. Using hardware timers, the data doesn't flow the way he wants it. =/

Message 21 of 21

(1,462 Views)