Different computer, different DAQ speed?

[cz_tine]

Hi..

I'm using USB 6009 as a data acquisition for my project..but when I use different computer, the DAQ speed changes abruptly.

When I'm using certain PC, it can run as fast as 100 Hz...but when I try to run it in my laptop, it can only run less than 4 Hz.

Had anyone faced the same issue? What should I do to optimize the DAQ speed?

Thanks a lot before...

[Dennis_Knutson]

You have not provided any information on what sort of task you are doing. Analog in, analog out, digital, etc. You have not  provided your code for someone to look at. You should know that all but analog in is software timed so other tasks are subject to pc, os, and programming style.

[cz_tine]

Hi,

Thank you for the reply. I'm using Analog output to drive the LED, and analog input to acquire data from photodetector.

Attached is my code for this pulse oximeter project.

Delay at each structure is 1 ms and I'm aiming for sampling rate of 10ms.

Thx!

[Dennis_Knutson]

That sequence structure is just not necessary.

As I mentioned, analog out is software timed and as the specs mention, the best you can expect is no more than 150 hz. Your analog in is in single sample mode and that is also software timed. Both are subject to a high degree of jitter. Your wait until next ms multiple is based on thr windows timer and that is not really reliable to 10 msec resolution either. A delay set to 1 ms is not going to be accurate either under windows. With all of those single writes/reads and waits, your current program would need LabVIEW real time.

[原上草]

Hm..what do u mean that I would need LabVIEW Real Time as I'm using single read/writes? In real time, I could not use DAQ card right?

[cz_tine]

ups..wrong account..

Hm..what do u mean that I would need LabVIEW Real Time as I'm using single read/writes? In real time, I could not use DAQ card right?