Trying to start signal aquisition and the write-to-file function in a timed loop

[jmvester]

Hi everybody,

I am trying to make a timed loop where I first aquire data (analog voltage) from my PCI-6024E card and then write this data to a measurement file (with the write to measurement file function). This in itself is no problem, but I have set the loop's iteration time to 2000 ms seconds, and the iteration time varies each time I run the loop (total variation is about 15 ms) even if I am doing the exactly same thing.  I suppose it is the DAQ assistant I use that creates this problem, but I am not sure.

The timing is very important, because I also generate a pulse in a parallell timed loop which is red by the this timed loop. And I need to know at which instant the pulse was generated. The important thing would be for the pulse generation and the pulse reading from the card to start at the same instant.
I am using LabView 8.5.
Can anybody help me with this?

-Jenny

[Jeremy_M]

Hello jmvester,

I would like to know how you configure your DAQ assistant and why you are using a 2000 ms iteration time for the loop. The matter comes from the DAQ assistant which must configure each time you call it. If you want to generate a pulse and measure it at the same time, you should synchronize your two functions. I advise you not to use DAQ assistant but low-level functions to build your code (DAQmx VIs). Otherwise, you can generate the code from the DAQ assistant by converting it to a standard sub-VI.

Regards, 

Message Edité par Jérémy Marliot le 03-03-2008 10:41 AM

[jmvester]

Hi,

I did understand what is wrong, and I did get it working with thouse low-level DAQ-vis.
Thanks,
Jenny