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PCI-5122: FetchForever on one channel, triggered acquisition on the other channel

Hello,

 

I want to write a C++ program for my PCI-5122 based on the examples, where the first channel continuously acquires a signal, as in the FetchForever example, while the other channel is doing a triggered acquisition. Is that possible at all? In GenericFetchForever.c I could find the following comment:

 

   // This example only works with one channel, so we make sure the user
   // didn't specify 2 channels or multiple records.

What exactly does that mean? It's not possible to have two channels doing a FetchForever? Or it's not possible to use the other channel for anything at all?

 

More generally, is it possible to configure one channel to use a software trigger, while the other uses the hardware trigger?

 

Thank you,

Frank

 

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Hi Frank,


What example are you using? Here's a resource that may help with other Fetch Forever examples to use if the one you have doesn't work for your purposes:

http://digital.ni.com/public.nsf/allkb/03726608568CB14786256F330071706D?OpenDocument

Sunayna R.
Applications Engineering
National Instruments
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Hi Sunayna,

 

thanks for taking the time to reply. Basically, what I would like to know boils down to the question whether the FetchForever example and MultiRecord Fetch More Than Available Memory can be used simultaneously, one on each channel? Can they be run in two independent threads, or processes, where each thread or process deals with one of the two channels? Can these examples be used in such a scenario, where the onboard memory would have to be split between the two channels / acquisition styles?

 

Thank you,

Frank

 

 

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Hi Frank,


I see what you're saying! That's an interesting question, and it doesn't look like we have a lot of documentation on that. I'll have to speak to some of my colleagues and see if I can get more information on the functionality of that example.

Sunayna R.
Applications Engineering
National Instruments
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Hi Frank,

 

I looked into it a little further, and unfortunately, it looks like you can't do two separate acquisitions on two channels of your scope. You'll have to use two devices to achieve the functionality you require. Hope that helps!

Sunayna R.
Applications Engineering
National Instruments
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Hi Sunayna,

 

many thanks for checking back on this with your colleagues so quickly. This still helps, as it will save me a lot of time trying, and maybe others too. We will consider alternatives, like using a second scope.

 

Best,

Frank

 

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