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Trigger Signal in NI 9215 w BNC




 I have a NI-9215 with BNC module connected to a NI USB-9162 carrier. I am planning to use the NI-9215 for data acquisition, but I need a trigger signal to time the start of the data input. The NI-9215 has 4 BNC inputs, but LabView does not allow me to set one of the port as the trigger. I would appreciate if someone can help me resolve this issue.



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Hi there,


I bet we can find a way to solve your application but the NI 9215 module does not have a hardware trigger circuit on it so triggering from an external source will not work.  How fast is your trigger signal?  There are a couple of options that I can see right now.  If your trigger signal is not too fast relative to the processing power on your machine, you can search for the trigger in SW and then begin displaying/logging the data once that trigger asserts.   The other option is to acquire from all desired channels at maximum desired sample rate logging all of the data.  You can then parse through the data afterwards looking for the trigger.  Most PCs should be able to sustain a continuous 400kS/s over the USB bus so you should be able to handle all of the data.  I recommend using a TDM(s) file format since it is a binary style that was designed for high speed data storage.


I know that these options may not seem ideal, but with the processing and storage performance of todays computers the same data can be captured and isolated without a hard trigger.


hope this helps...let us know if you have further questions.





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