INTRODUCTION:
I have two NI-PCI-6014 cards (Dev 1 and Dev2 )and I'm trying to count the TTL signals coming from two Avalanche Photo Diodes (APD). For each photon detected, each APD generates a ~30ns TTL pulse. The frequency of pulses depends on the intensity of light the detector sees.So the signal frequency (random) can vary from 100Hz (dark counts, no light) to 1-5 Mhz
The critical thing in my application is that I need to be able to count the pulses at the exact same time bins (typically 1ms) so that I can make comparisons between the signals detected by the two detectors. There shouldn't be any unknown time delay between two time bins.
On NI-PCI-6014 cards, there are two counters and I guess it makes sense to use 2 counters on one of the cards as they would be on the same card.
As a starting point, I first wanted to count pulses from one detector.I tried to use "Count Digital Events- Finite-Buffered-Ext Clk.vi". I couldn't find a way to use the 20Mhz tiembase , but instead generated a 10MHz digital signal using Dev1 and used this as the SOURCE of Dev2/CTR0 ( counter on second card) while connecting my data signal to GATE of the CTR0 as a Sample clock.
For low signal (less than about 30Khz), this worked, but beyond 30khz, I started to get error (200028).Then I started using "Count Digital Events- Continuous-Buffered-Ext Clk.vi". This time the treshold for error was about 300Khz, and I started to have errors: 200279 and 200141.
QUESTION:
Is it possible to count pulses from 2 APD's (random pulses changing from 100Hz to 1-10 Mhz) simultaneosly using one or two 6014's ?
Would I need some thing like 6601,6602 so that I use 2 counters for each APD, total of 4 counters ?
Any suggestions from someone who might have some experience on this?
Thanks
