programming/setup of DAQmx for DAQ Express

[maurerm]

Hi,

       I am trying to recreate the DAQ Express VI in LabVIEW 8.2 with the DAQmx vi's.  When I use a regular DAQ Express VI I get a dynamic data array of 10000 elements due to my sample rate.  When I recreate the Express VI  with DAQmx vi's I can only read in a 1D array with one value as opposed to the Dynamic data which has an array of 10000.  Am I missing a setting on the DAQmx Read vi??  Also is this the correct setup to replicate the DAQ Express VI with the DAQmx vi's (see attached)??  I am reading in on a NI SCXI 1530 using an analog accelerometer.

[Robert_F]

Hello Maurerm

Once you have created the Express VI (DAQ Assistant) that has the functionality that you want, you can Right-Click on it and select Generate NI-DAQmx Code.  If you set your Express VI to continuous acquisition mode, LabVIEW will ask you to put it in a while loop.  Once you generate the code, you will have two while loops.  The while loop created from LabVIEW when creating the Express VI is unnecessary. 

The Dynamic Data coming from the DAQ Assistant is just like a waveform data type.  They both can have dt and t0 components associated with your data.  You could change to DAQmx Read to waveform data type (Digital >> Single Channel >> Multiple Samples >> Waveform). 

The samples to read is going to be your buffer size and will determine how many samples the DAQmx Read is going to acquire every time that it is called.  Normally, you would like this value to be about 10% of your sampling rate.