High-Speed Digitizers

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6115 and post-triggered acquisition

I would like to use the 6115 card to sample an analog input at 6.4 MHz. It appears as if I should use the typical post-triggered acquisition mode as shown in Figure 4-10 of the 6115 manual. Therefore, I am planning on routing my 6.4 MHz sample clock to the STARTSCAN input of the 6115.

I would like to possibly use an internal CONVERT* signal. My question is, what is the delay between my STARTSCAN rising edge and the actual A/D conversion? Also, is the STARTSCAN pin the best way to sample the input? Is there a better way? Do I need to use the actual CONVERT* input?
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Hello;

There are two main ways of doing that. You can have your external signal routed to the StartScan pin, and that will control the start of a new scan. When a new scan is started, the internal counter that generates the Convert* signal is triggered. That method will take at least 10n seconds delay after you have the StartScan signal coming in, so the ADC will do one convertion.
The other way is to have the external signal tyed straigh to the Convert* pin. With that method, as soon as the external signal comes is, the ADC do one convertion, without any delay.
Hope this helps.
Filipe
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I'm curious to know where you got the 10 ns number. Did you talk to an NI representative? If I use the CONVERT* pin, do I also have to use the STARTSCAN pin just before (have to clocks)?
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