The modifications in this attached VI will save data as an ascii file
but for such a larger scan rates and higher sample count, i would recommend file saving in Binary file format.
Go to examples>>hardware input output>>DAQmx>.analog measurements >voltage >>cont acq&graph volt-to file(bin).vi and read data using graph acquired binary data
For traditional DAQ VI's, examples>>hardware input output>>Traditional DAQ>>stream to disk examples
These should serve your purpose better
Regards
Dev