How can I use a gating counter and an input counter in countinuous mode

[Franco_Giammaria]

Hi,
I have a PXI 6259 with LV 7.1 and I am trying to generate a retriggerable finite pulse train (using Counter 1) in order to gate the input counter (Counter 0).
For generating I found : Gen Dig Pulse Train-Finite-Retriggerable.vi that works well.
For Counting: Count Digital Events-Buffered-Continuous-Ext Clk.vi that is OK.
I am trying to merge these examples to generate and count on the same program, but I don't now how !!!

[Kevin_Price]

Unfortunately, when you generate a "finite pulse train", both of your board's counters get used to create it.  One of them produces the output signal while the other one controls the generation time (which in turn controls the # of pulses).  So you won't have any counters left.

Nevertheless, if you can describe more about what you're trying to do and why you need to do it, there may be some other options available.   There's a more complicated way to generate pulses using one of the port 0 digital output bits for example.  What are the signals you want to perform buffered counting on?  How frequently do you need to retrigger? 

-Kevin P.

[Franco_Giammaria]

Thank you for your answer,
I am trying to count TTL edges from my PMT (Photon counting). The light source is a 5 KHz pulsed Laser.
In my appliction I need to count:
- only when the Laser Pulse is on (DAQmx Start Retriggerable);
- for each laser pulse we want to count 25 times dividing the counting edge by 25 slices (generating 10 MHz Finite pulse train);
In this way we obtain a 25 element array for each laser pulse.
To improve the signal to noise ratio we want to sum up all the arrays, coming frome several laser pulses, element by element.
This is a typical counting problem on time florescence decay measurements or LIDAR applications that people usually solve
by Multichannel Scaler.

[Kevin_Price]

So, once every 200 microsec (5 kHz laser pulses), you want to trigger a finite pulse train generation.  That pulse train will pulse 25 times at 10 MHz freq.  You would like to take a PMT count sample on each of these 25 pulses.  Is this correct?  If so, sorry, I mainly have bad news.

1. (Not hard but costs $)  The speeds you need prevent you from using the AI, AO, or DIO features of your board to compensate for the limited # of counters on the M-series 6259.  You really do need 3 counters here, 2 to generate a retriggerable finite pulse train and 1 to buffer count samples.  A dedicated counter/timer board like the 6602 may be worth considering.

2. (Hard.)  However, based on various threads here I'm quite doubtful that you'll be able to achieve counter sample rates of 10 MHz.  Most of the discussion seems to set a ceiling in the low 100's of kHz, and reliability will suffer as you approach the limit.

-Kevin P.