Do you need "DAQmx start task" vi to read from a NI DAQ device (NI 9205)?

[sticyfinger]

I have a NI 9205, which I am using to get a waveform data. To get started quickly I used the DAQ assist Vi. The code below (FIGURE 1) is what the DAQ assist VI looked like when I convert it to LabVIEW code and did some minor adjustments.

When I looked online to see how to get data from DAQ devices, a lot of sources use the DAQmx Start Task in figure 2.

Does using DAQmx start VI make a different?  Does using DAQ assist in loop give you a lack of performance?    If yes, will figure one have a lack of performance too since it is basically the DAQ assist code?

FIGURE 1 

[0utlaw · Accepted solution]

Hello sticyfinger,

From the Help for the Start Task function:

"If you do not use this VI, a measurement task starts automatically when the DAQmx Read VI runs. The autostart input of theDAQmx Write VI determines if a generation task starts automatically when the DAQmx Write VI runs.

If you do not use the DAQmx Start Task VI and the DAQmx Stop Task VI when you use the DAQmx Read VI or the DAQmx Write VI multiple times, such as in a loop, the task starts and stops repeatedly. Starting and stopping a task repeatedly reduces the performance of the application."

Hope that helps!

[sticyfinger]

thanks!!!