fast triggered acquisition (200 kHz) with PXIe 5122

[josch1987]

Hi, 

I am using a PXIe 5122 to acquire data from both channels (CH0,CH1). The acquisition is triggered by the external trigger. The events for triggering are random and I would like to reach a sensitivity of 200 kHz (so the system should be able to to record events which occur 5 us apart). For the example VIs from NI scope (like EX Timestamps.vi or multifetch) I am only reaching a sensitivity of 80 kHz. For each event (sample) only one record from each channel is needed.

What can be done to increase the sensitivity?   

[Adam_S · Accepted solution]

Hi,

According to the specifications of the PXIe-5122, the minimum trigger rearm time is 12 microseconds which is likely why you are seeing an upper limit of approximately 80 kHZ (would be closer to 83 1/3 kHz to be exact).  

http://www.ni.com/pdf/manuals/376937a.pdf#page=14

This is the fastest you would be able to receive a trigger and then rearm.  With the Time-to-Digital Conversion circuit turned off (TDC) you can improve this to better than 330 kHZ response time.

More on this method and some other suggestions for improving the rearm speed can be seen in this related forum post:

http://forums.ni.com/t5/High-Speed-Digitizers/Improving-ADC-pulse-aquistion-time/td-p/958520

Hope all this helpful!

[josch1987]

Thanks Mada, 

this was very helpful. Now the acquisition rate is high enough for my application!!!

[Adam_S]

I'm so glad to hear that you are able to move forward!  Best of luck!