Counting device suitability

[PhotonCoder]

Dear LabView community,

I am currently working on a project using a photodiode that will output a pulse train. As a first approach we are simply interested in the amount of pulses in a certain time interval. For this we would like to use the counter input of a NI-USB-6212 device which has an internal baseclock of 80 MHz.

The pulse train put out by the photodiode will have pulses of a total pulse width of ~ 10 ns and the device can output pulses every 30 ns, so it can have a maximum frequency of 33 MHz. The signal might also be aperiodic however, that's why I'm mainly interested in the amount of pulses, not the frequency itself.

Would the device listed above be suitable for this application or do we need to look for something else? Advice is greatly appreciated.

Best

PhotonCoder

[Kevin_Price]

Looks likely to be a no.

The specs give a min pulse width of 20 nanosec.  Or 10 if you use prescaling, but that'll divide the signal down by at least a factor of 2 -- you'd only register 1 count for every 2 pulses.

Even if you did that though, there's also a max frequency spec (see "external base clock frequency") of 25 MHz.  Technically, it's *conceivable*, but far from assured, that support for a high freq timebase signal is more limited than for an edge-count signal.   I'm merely speculating though, thinking that a signal designated to act as a timebase clock would need to be able to pass through additional circuitry than if it were designated to act merely as a signal whose edges are being counted.

-Kevin P