USB 6008 digital input

[giovanna]

Hi,

I got a usb-6008 device.

I need to acquire a digital signal with an acquisition time of Microsecond (and this device should be able to do it...).

Anyway, I created a Labview software with a While loop for recording the signal and the acquisition time and I save the results in a Txt file: when I open the file the difference in time between two acquisitions is Millisecond at least!

Is it due to my software? Is Labwiev not able to run a step of the while loop in less than ms? Or I should use the analog input?

Many thanks,

Giovanna

Ps: is it possible to use an external clock with this device? I tried but I got error!

[AnalogKid2DigitalMan]

Giovanna:

Some bad news on both fronts: The 6008 digital inputs are not hardware-timed to be able to capture 1us intervals, and the 1msec time difference you are seeing is a limitation of Windows. The analog input maximum sampling rate is also too slow to capture the signal. I'm not familiar with NI's offerings for high speed digital inputs, hopefully someone can suggest some options.

[giovanna]

Hi...

so just to be clear...

I need to sample at about 100microsecond rate.

And it looks like I cannot do it.

Now I have one more question: If I use the analog input can I tune the sampling rate? and How? or is a fixed one?

Many thanks

Giovanna

[Dennis_Knutson]

Yes, you can adjust the sampling rate but as already mentioned, the analog sample rate is not fast enough either. As listed in the manual, the max sample rate is only 10 ks/s.