sampling rate on 6601

[Kemot]

Hello.
Im using 6601 to measure a position and velocity with quadrature encoder. I have to set sampling rate, and here my problems begins. I'm setting rate on 1 ms, so after 1 second a should have 1000 samples, but i havent. The main idea of application is - set sampling rate, then save possible to set number of samples, into file.
Regards
Kemot


Message Edited by Kemot on 08-06-2008 03:49 AM

[S_Hong]

Hi Kemot,

If you set your sampling rate to 1 kHz, then you should be acquiring 1000 samples every second into your buffer. Now depending on how many samples are being read from your buffer, it may appear as though you are reading more or less samples. If you want to return 1000 samples every time you call a DAQmx read function, you must set the "number of samples per channel" input to 1000. Note that the DAQmx read function is simply taking the data from your buffer into application memory and so your hardware is always be sampling at 1 kHz without missing any data.

Also, I would like to point out that there are tons of great DAQmx shipping examples in LabVIEW that you could refer to. You can view these in your Example Finder by accessing it under Help » Find Examples.... The example we are particularly interested in would be under Hardware Input and Output » DAQmx » Counter Measurement » Position » Meas Angular Position-Buffered-Cont-Ext Clk.vi.

I hope this helps,