retriggerable buffered event counting

[Jofre]

Hi again,

I have been thinking... I was thinking about the algorithm to extract the information in the case of using two counters... and I think that, at least for my case, it would be to slow. I explain myself better. I am using a particle detector to detect neutrals, coming from the neutralization with background gas of positive ions in an ion trap. The fact of reading this neutrals are signature of the trapping itself and I can not afford to loose(not count) any of them!!!. I am using two other counters to generate the injection of the ions, by sending a "Pulse-Train Generation" (let's the ions pass a delfection voltage) that triggers a "Retriggerable Single Pulse Generarion"(that lowers the entrance wall potential to trap), the last one tigger my "Buffered Event Counting". So the period of the wished trigger for my ideal "Retriggerable Buffered Event Counting", is generated by the card itself. So far, in theory my program should do the job, extremely fast and with and an accuracy of 50nanoseconds (remember that I needed the time precision to know exactly when the particle has hit my detector).
The problem arise, I think, from the fact that the 5KV power supply is been ask to deliver high voltage to fast (our pulser, from a German company have rise times of 5-10nanoseconds at 3KV) there are spikes going throug the whole system and, somehow shift the time base. But my algorhitm have not "protection" against that and get's shiftted, so i see two (or three or four...), neutral peaks instead of just one (I accumulate the data). I have been looking to my data and i found a signature (the injection of ions get reflected into a burst of neutrals at the start of the experiment) so I will use this signature for manually (usign Origin6.1) to re-shiftted to the correct time.


I know that is not exactly about Labview, but as I am not going to use any of your suggestions,(and was me who asked for help) I thought I own you an explanation.

Thanks Mark and Kevin,

Best regards, Jofre.

[falkpl]

You should have no problem with this I have 5 counters of a 6602 counting in semi-buffered event counting mode which all share a trigger (all use the same gate pfi pin)and running in a retriggerable mode. I used a 6602 and LV7.0 and daq-mx. I agree that once you switch and get used to MX you will like it but it is a steep learning curve and some of the member settings are hard to find or had confusing names. I was able to count events (TTL pulses from 4 photon counting tubes and one clock line) between trigger events. One problem I did encounter was that the daq my filtered out null events (when no pulses were counted) by default so I had to set CI.DupCountPrevention to FALSE. Synchronizing the channels was no problem, just make sure that you start all event counters before you start the triggering. One additional warning with buffered event counting is that if you are going to collect at many kHz from more that 3 channels you only have 3 DMA resources and I have found that interrupts to cause problems in such cases. Since you only are looking at 2 channels right now this should not be a problem.

Paul