External clock for varing the sample frequency

[Alejo1]

Hi,

I´m using a external clock for varing the sample frequency in my aplication. I am scaning four chanels with a PCI-6133 begining with 1 Mhz and going down with a generator. I want to save the data to a file but I don´t get the rigth sampling time. Is there any posibility to transfer the sampling pulse to the same file where I am saving the information as x-value?

Thanks.

[Andre_Saller]

If you are using an external clock, the Analog input does not anaylze or measure the clock you are using, so there is no easy way to get the used samplingrate.

Best would be to connect your clock-signal to acounter/timer in parallel, and use this counter to measure the freuqnecy of your clock.

Hope this helps!

[Alejo1]

Hi Andre,

Thanks for your suggestion, but I'm quite new with LabView and do not understand the idea. I was trying to measure the frequency of the external clock by using the ctr1, but nothing happens. My problem is, i get the data from the analog chanels, but I can not make a Graph because I do not when the data were taked. I was also trying to create a kind of clock and the add the time column to the file, but I am not sure how can I do that. I am posting my vi, It wold be nice if somebody has any idea. The idea in the vi is to measure four ai chanels, first I can see how the values look like an then by pressing the button the aq. begings. I generate a pulse in ctr0 to activate the external clock and its signal is recived in PFI7. As i said before, the frequency of the clock decreases automatically from 1 MHz until ca. 100kHz.

Thanks in advance

Message Edited by Alejo1 on 12-05-2006 07:49 PM