Trigger with falling edge and then with rising edge

[zqhector]

Hello,

I wonder if you guys could please help me with the following:

I want to trigger on the rising edge of a square TTL signal, via PFI 0 of a USB-6008. Then, capture 16 samples of ai0. After that, trigger on the next immediate falling edge of PFI 0 and capture another 16 samples of ai0.

So far, I can either trigger and capture on a rising or falling edge, but, I have not found a way to trigger on both adjacent edges in sequence: first on the rising and then on the falling one.

Thanks a lot !!!

Hector

[SunainaK]

Hi Hector,

I found an article which decribes how to trigger on both the rising and falling edge using a retriggerable single pulse generation.

http://digital.ni.com/public.nsf/websearch/5A2DC5CF7246E08386256B79006279BC?OpenDocument

Let me know if you have any further questions!

[zqhector]

Thanks a lot for the help Sunaina !

I enventually got it to work.

In my system, I have to do measurements of 16 analog channels once I receive the interrupt.

I got to the point where I trigger on the interrupt edges I want. However, I can only do it for one channel. The width of the analog channels is of 500 us and they are synchronous. The USB-6008 seems like not fast enough to measure the 16 channels in less than 500us. I found that it takes it at least 1 ms to do one channel and then go do another.

My next question to you, is there a piece of NI hardware where I can make 16 analog measurements in less than 500 us ?

Thank you,

Hector

[SunainaK]

Hi Hector,

I found hardware with 16 analog inputs and an analog input sample rate of at least 1kS/s:

http://sine.ni.com/np/app/main/p/bot/no/ap/daq/lang/en/pg/1/sn/n17:daq,n21:41,n1:7850,n13:7371/

Hope this helps!