data acquisiton with pci 6251 board !!!

[gfhfh]

Hi,

I am currently trying to acquire my system's voltage and current values from four channels with PCI-6251 DAQmx card at a sampling rate of 20000 S/sec. My program works 10 sec and collects 200000 samples.I would like to be able to save the incoming signals in a matrix (each column correspond to one input) that I want to use in MATLAB order to do some further off line calculation.
I have been able to display the graphs. I have saved some data into the MATLAB format BUT when I started the labview program that i have made, it acquires the signals very bad. I think there is a loss of data during the acquisition.
I have attached my acquisition VI and the picture of data acquired front panel linked to it. If someone can tell me what to do, I would greatly appreciate.

Thanks

volkan.

[gfhfh]

sorry i forgat VI attachment

[gfhfh]

and screen capture of my steady signals, as you see there is transient parts in some places. but in real system there is not..they must be pure sinusoidal

[Ayman K]

Hello Volkan,

I looked at your VI and used it with many different signals (PCI-6251). It worked great. I didn't get any transient responses. Could you please run the attached VI and test only one channel and gradually increase the number of channels used to see the response. The M series card has the capability of sampling up to 1.25MS/s, so when using 4 channels, you could sample up to 312KS/s. You should not be seeing this clipping with the sampling rate you are using (20KS/s). Please monitor the signals that you are feeding into your DAQ card with a scope to see if the signals are clipped. Also, please check test the different channels in MAX to see if each channel is functioning properly. A test of your task should reveal if any of the channels is malfunctioning.


Thank you.

[Support]

Sorry I forgot to attach the VI.