Indexing arrays for DAQ

[Sanjeevs]

Hello,

               I am trying to get 8 channels of data from DAQ assistant to be written into arrays and then saved on the disk.   

My requirements are:

1) When an external trigger occurs, DAQ assistant  acquires data from 8 channels  for 1 second (4096 Hz sampling frequency, so 4096 samples)

 2) Write the 4096 samples from each of the 8 channels, into  8 separate arrays

3)  Write the array data into 8 files 

I have these questions:

1) The DAQ assistant does not have an external trigger input. How can it be triggered?

2) How can I index the array into which I am saving data?  ( I have 4096 samples being written into 4096 elements of an array in one second.  How can I ensure that the nth sample gets saved in the nth slot on the array? ) 

[Dennis_Knutson]

Based on this question and another , I think you have some very deep misunderstandings. By definition, an external trigger is a signal that you physically connect to your DAQ hardware. You would use the DAQ Assistant to configure your hardware to recognize this signal and start the acquisition (assuming your DAQ hardware is capable of external triggering). It is silly to think that the DAQ Assistant would have an input for an external trigger. The wires of a LabVIEW program are not at all physical connections. The DAQ Assistant has a tab page (called Triggering) for configuring your hardware for this external signal.

Array manipulation and file saving that you want to do is one of the most trivial tasks in LabVIEW. With the Write to Measurement File, you can configure it to write to a series of files so all you have to do is connect the Signals output of the DAQ Assistant to the Signals Input of the Write to Measurement File. You could also simply wire a Split Signals function to the Signals output of the DAQ Assistant. You would then create 8 outputs of the Split Signal function and wire them to 8 separate Write to Measurement Files.

I strongly urge you to first spend some time with the LabVIEW tutorials and the DAQmx Getting Started links so you can understand the way software controls your hardware.