I am searching for a hardware recommendation. Here's what the hardware should do: notify a PC program to run a subroutine upon detection of a TTL pulse (digital input change).
So I need one 1-bit digital input, and the device should communicate with a computer via USB. The TTL pulse voltage is about 4.7 V. Since the synchronization must be fairly precise, the delay should be on the order of 1 ms or less. Therefore the hardware should have a sampling rate of at least 1 – 10 kS/s.
I purchased the USB-6501 not realizing that it doesn't have any triggering or interrupt functionality, and now I don't think it will work for my application. I could constantly poll one of its inputs with my software to check for a change in value, but that would be relatively slow and hog my CPU. I would prefer that the device triggers or provides some kind of interrupt to my software application. I am considering using some NI software, but right now I'm using the session-based interface of the Data Acquisition Toolbox in the latest version of Matlab (R2013a, 64-bit) on 64-bit Windows 7.
I think either the USB-6008, USB-6009, or USB-6525 might be a good option, but I'm not sure. I don't fully understand the difference between the triggering/interrupt capabilities of the USB-6008/9 and the USB-6525. Any advice?