Slow performance DAQmx function calls

[Pacsoft]

Hi,

We are currently using LabwindowsCVI to write an application that uses the latest DAQmx driver 8.6.1 to control a CompactDAQ chassis. When we run our application in a desktop, it runs perfectly. However, when we run it in a laptop, the DAQmx functions take a looooong time to execute. We tried several desktops with good processors and good memory as well as several laptops with good processors and good memory and the performance problem is seen always when a laptop is being used. Laptops gets slowed down when the DAQmx functions, which in turn get translated to USB calls through the DAQmx driver, are executed. The rest of the application is being executed fast and with no flaws. We changed the thread priority from normal to time-critical and execution got better, but is still taking a long time to execute. The application is very lightweight and is not doing anything complex.

Any ideas ?

PacSoft 

[jaced]

Hi,

I have a few questions as well as a couple of suggestions to try. First are the USB ports on the laptops USB 2.0? Are the Laptops all the same brand/ model of laptop? When you say slowed down how are you monitoring the execution speed? And finally you mention that the “rest of the program” what is this other part doing? As far as troubleshooting steps go I would begin with an example program which can be found by Selecting Find Examples from the LabWindows/CVI splash screen>>Selecting Browse>> Hardware Input and Output>>DAQmx>> and the appropriate category. Try one of these examples that perform the function that you are attempting to do and see if the performance is different on a laptop vs. desktop. Another step to try is minimizing the number of other USB devices which may be connected as the USB bus is a shared bus. I hope this helps!