I am using a USB-6341 to measure the counting rate (pulse events per second) of single photon detectors.
When I checked the edge count function of the USB-6341 using pulse generator as a counter source,
it seems that the USB-6341 can't measure the higher frequency than about 25 MHz.
I used a 1 Hz external clock for a sample clock source, so the measured counter value means the output frequency of the pulse generation.
The counter value seems to be saturating around 25 MHz even for the higher frequency input to the counter source.
25 MHz is quite lower than the 100 MHz timebase of the counter card.
What is the maximum counting rate (or the maximum frequency) that can be measured with USB-6341?
Is there any bandwidth limit in the input area of the hardware?