DAQ buffer allocation

[sergey 671]

The question is regarding the buffer allocation when working with DAQ (for example, using the "buffer size" input in AI config VI).

Platform: W2K, LabView 6.02, PCI6071E DAQ board.

1.Where this buffer is allocated ? In the computer's memory (and the boards writes into in, using DMA) or in some on-DAQ board memory. If so, how can I know how much memory is installed on my DAQ board ?

2. Are there any limitations on the buffer size ? What are the reasons for choosing it (DMA limitations, etc.) ? I have 64 channels and want to store 1000 scans x 10 times redundancy for CPU load spikes that is 12 bit x 64 x 1000 x 10 = 7.5 Mb - is it ok ? And 100 scans (750Kb) ?

Thank you,
Sergey.

[Filipe A.]

Sergey;

Once you configure the buffer, a memory space on your computer RAM is allocated and reserved for that task. The on board FIFO of the DAQ board is there to allow one to acquire multiple points before doing the DMA transfer to the computer memory.

There isn't a memory limitation but the ammount of memory that is free at any given time. In case you have the 7.5Mb of memory free, at the beginning of the acquisition, you should be ok.

Regards
Filipe A.
Applications Engineer
National Instruments