Lack of externally clocked input with USB 6008

[was1984]

I'm a bit confused about how to retrieve digital data without an external clock.  I'm assuming there is some way to do this, or this device wouldn't advertise digital input, but I don't understand how exactly it would work.  Apparently my only option is "on demand."

I'm taking frames of data occurring about every 1 ms with a clock frequency of about 950 kHz.  I have this successfully implemented with a more sophisticated board using a clock from the data source.  We now want to translate this to the USB 6008 so we can use the OEM 6008 as a daughterboard for our data source. 

[Dennis_Knutson]

The digital I/O is strictly software timed as clearly described in the specs. You should contact your sales engineer to discuss OEM options with a board that meets your requirements.

[was1984]

I understand that it is software timed.  We ordered the board anyway to see if it would work.  I'm trying to understand how exactly software timing works for input, and also what the frequency limits are going to be.

[Dennis_Knutson · Accepted solution]

Software timing depends on the software you are using, the pc, the os, etc. Every time you want to do a read of a line, you do a DAQmx Read. Absolutely no correlation to any defined time because windows is not even close to deterministic. You will maybe  readings in the low khz range.