Simultaneous trigger of two counters in buffer period measurment

[perroudt]

Hi, I am currently using a PCI6602 Counter/Timer board in buffered period measurement configuration. I would like to synchronize the starting of two counters. Unfortunately in buffered period measurment the gate on both counters is already connected to my two detectors that do not send a signal at the same time. What is the best configuration? Is it possible to trigger the two counters using the auxilary line and then measure the period on each gate? Thank you

[Filipe A.]

Hello;

You have two options to solve that problem. The first one is by using the same external pulse to trigger both counters. By doing that, you will have a hardware synchronization.
If you don't have or don't want to use an external pulse to trigger both counters of, you can synchronize both per Software. There is a really good Application Note you can refer to, in order to get familiar on how to synchronize operations by Software.
I'm attaching a copy of the App Note to this link, for your convenience.
Hope this helps.
Filipe

[perroudt]

Thank you very much for your fast answer. I am interested in the hardware synchronization. However how should I proceed since the gate on each counter is taken by my signal and the source by the internal timebase? Is there any other line I can use? If yes what should I change in "buffer period measurement" such as the counter is triggered by this hypothetical line?

[Kevin_Price]

Just to expand a bit:
1. Install the Counter/Timer Palette update:
http://digital.ni.com/softlib.nsf/websearch/abc2de0382fb157a86256ad90068986e?OpenDocument

2a. Once installed, place the vi named "Counter Start Trigger (NI-TIO).vi" (found under the "Util" icon in the Counter palette) into the config chain of both the counters you are using for buffered period measurement. Feed the same Trigger Spec cluster to both. (Note: trigger config must occur *before* starting the counters!)

OR

2b. Make use of the new multi-counter config vi's under the main Counter palette. They appear handy for such circumstances. Caution: Unlike choice 2a which I have done numerous times succesfully, I have not yet tried the multi-counter vi's. A
brief peek at the one for configuring the trigger looks questionable to me -- there is no place to wire in the trigger spec! (Sure,
it's easy to add it, but if *that's* missing, I have to wonder how thoroughly the stuff was tested, knowwhatImean?).

3. If an external TTL trigger signal is necessary or convenient, set config specs to use it. If not, you're still ok and here's how to do it without a screwdriver: set trigger selection to a PFI line corresponding to the output of an otherwise unused counter. You can then simply issue a single pulse on that counter via software to create a trigger that guarantees both your buffered period measurements are using the same instant as time=0. Just be sure that both your buffered period counters are configured *and* started before generating the single trigger pulse.