Digital I/O

cancel
Showing results for 
Search instead for 
Did you mean: 

external digital input start and done events

Dear NI members,

 

we are working on a microscope driving application, written in C by using the NIDAQmx driver. We create a digital input task and we asign a Change Detection event for it. From the microscope a 8kHz signal will arrive every time the scanner starts acquisition and that signal will stop after acquisition is done. To detect the start point we are looking for the first change in signal from low to high. We are having issue of detecting the end point, as the number of 8kHz pulses sent by the scanner can be different. What is the best way to detect that the signal is not arriving anymore? 

The card we are using is NI PCIe-6321.

Thank you in advance for any ideas.

 

Best,

Georgi

 

0 Kudos
Message 1 of 2
(3,831 Views)

Hi Georgi,

 

if I understand correctly, what you need is to implement a start and a stop trigger for your aquisition.

 

Have a look at this Knowledgebase Article, it might answer your question:

How Do I Use a Digital Trigger in LabVIEW to Start and Stop Acquiring Data? - National Instruments
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019MiHSAU&l=en-US

 

Also, possibilities are listed in following WhitePaper:

Tips and Techniques in Data Acquisition Triggering - NI-DAQmx - National Instruments
https://www.ni.com/en/support/documentation/supplemental/21/ni-daqmx-data-acquisition-triggering-tec...

 

I hope this helps!

Best wishes, 

Monika

0 Kudos
Message 2 of 2
(3,753 Views)