Trigger reaction time

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Gutsnuts
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Joined: Wed Mar 20, 2019 4:37 pm

Trigger reaction time

Post by Gutsnuts » Wed Mar 20, 2019 5:24 pm

Hi,
I'm using a Picoscope 4224 to trigger an a acoustic peak signal under streaming mode. The signal has a frequency of about 150kHz so I measure with intervals of about 2 microseconds. My program is based on PicoScope4000ExampleStreaming on GitHub. To get only the data when the trigger has occured I use the IsTriggerReady function (triggered and triggeredAt) to extract the relevant data (Pretrigger and Posttrigger) in a separate queue. The whole program works quite well (at least i hope so :wink: ) but I realized that the trigger reacts with a delay. When i check the data that is measured continuously (but not copied in the queue) in the "get data"-loop the trigger conditions are meet many loops before the IsTriggerReady shows a true at its output. The delay is curious but no problem because with the trigger index it is still possible to extract the right values. But sometimes (I haven't found out what the requirements are) the IsTriggerReady function reacts exactly when the data buffer is overwritten one time. So the trigger index is still correct but the values are have changed. This behavior changes with the size of the data buffer, so if i enlarge the data buffer the delay gets bigger too.

My questions are:
1) Is there a delay for the IsTriggerReady function or should it react immediately after the data event of the trigger is copied into the data buffer and checked by the function?
2) If there is a delay can you shorten it with a smaller execution time of the loop or something like that?
3) Is there any explanation for the "one complete data buffer" delay? :(

I hope I have explained my problem understandable and appreciate all ideas and possible solutions. :D

Thank you,
Florian

Gutsnuts
Newbie
Posts: 0
Joined: Wed Mar 20, 2019 4:37 pm

Re: Trigger reaction time

Post by Gutsnuts » Thu Mar 21, 2019 3:30 pm

Okay, I have now implemented a own trigger logic into my labVIEW programm. It slows down the loop iteration rate of the data acquisition a little bit, but now the trigger is activated in the same iteration in which the corresponding data is acquired. Because of that it's no longer necessary to get an answer to the reaction time of the IsTriggerReady function. But it would be still interesting to hear a solution/answer to that problem.

Flo

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