analog trigger with NI USB-6218

[JulienBillard]

Dear all,

I just recently acquired a NI USB-6218 with which I am attempting at recording pulses induced by interacting particles in my detector. Unfortunately, I just came to realize that this the NI USB-6218 does not have the capability to do analog trigger on its own. Only digital trigger is possible. However, I really need to be able to acquire data (pulse) from my particle detector in a trigger mode on the analog input when the latter goes above some given values (in volts). I need to acquire pre- and post-trigger data to perform acurate data analysis.

Even though this device does not handle by itself this analog trigger mode, is there any way around this to still be able to do it?

- Do I need to create my own circular buffer?

- Can I use a condition (if analog input greater than some value) to generate a digital output than I can then connect to one of the digital inputs to create a digital trigger?

- Is there any better solution?

Many thanks for your time and consideration.

Best regards,

Julien

[Niki']

Hi JulienBillard,

Unfortunately, you won't be able to do accurate data analysis without analog trigger. You can still use the second configuration you mentionned but because of the difference between your hardware sampling rate and your software sampling rate, you'll have a delay of a few ms before your programm detects that your analog input went above your trigger value (for instance) and you'll lose precious data. But if accuracy isn't really important you can have a try with this configuration.

Regards.