Mark,
thanks for your kind answer.
I think I get what you mean. I'll try to use DAQ occurence VI.
Thank you again,
Chang-Kwon
"markwysong" wrote in message
news:506500000005000000C9530000-1007855737000@exchange.ni.com...
> Chang-Kwon,
>
> I believe that your problem doesn't really lie in the fact that you
> have two loops, I think it is rooted in how you are doing your data
> acquisition.
>
> First, let me make the assumption that you are using buffered
> acquisition for your data (you must be to get 250 kHz). When you do
> your buffered acquisition, are you using DAQ occurrences to see when
> the buffer is full (or has a specific amount of data in it) before you
> perform your AI Read?
>
> What I'm getting at is when you perform a buffered
acquisition, you
> call the AI Read VI to get the data out of the buffer and into
> LabVIEW. If you ask the AI Read for an amount of data that is not
> available in the buffer yet, it will consume the "data acquisition"
> thread until the data IS available. Therefore, any other data
> acquisition VI's that you are trying to run will be halted until this
> operation completes.
>
> The way to get around this is to use the DAQ occurrence VI. This VI
> will halt until the amount of data is available in the buffer, but it
> doesn't consume the data acquisition thread while it is waiting; when
> it returns that the data is ready, then you can perform your AI Read.
> This allows you to have more than one data acquisition going on in
> either one or more loops.
>
> Hope you understood that. Let me know if I can help you further.
>
> Mark