How do I perform a double buffered acquisition from a VXI MIO board with a GPIB-VXI/C or VXI-1394 Controller?

Primary Software: LabWindows/CVI Development Systems>>Full Development System
Primary Software Version: 3.0
Primary Software Fixed Version: N/A
Secondary Software: LabWindows/CVI Development Systems>>Base Package
Hardware: VXI/VME/MXI>>VXI Data Acquisition and Instrument Modules>>VXI-MIO-64E-1, VXI/VME/MXI>>VXI Data Acquisition and Instrument Modules>>VXI-MIO-64XE-10, VXI/VME/MXI>>VXI Interfaces>>VXI-1394, GPIB>>Plug-in Controllers>>GPIB-VXI/C, VXI/VME/MXI>>VXI Data Acquisition and Instrument Modules>>VXI-MIO-64E-1

Problem: Niether the GPIB-VXI/C or VXI-1394 controllers support shared memory, which is required for performing a double buffered acquisition.

Solution: You must install and configure a RAM SIMM on the VXI-MIO module and then programitically configure the NI-DAQ driver to use this memory for performing a double buffered acquisition

In CVI, use the Set_DAQ_Device_Info function to select onboard memory. For example:

error = Set_DAQ_Device_Info (1, ND_VXIMIO_SET_ALLOCATE_MODE,ND_VXIMIO_USE_ONBOARD_MEMORY_AI);Currently, this function only works with the "easy I/O" functions, not the rest of the NI-DAQ functions. The two examples (ai_acq test.c and ai_async test.c, attached below) are two of the "easy I/O" examples with this modification.

In LabVIEW, use the Buffer Configure.vi. See the LabVIEW example onboard memory test.vi, attached below.

Note: Some customers have reported success with these configurations, but they have not been officially tested and validated by National Instruments and are not guaranteed to work with currently released drivers.

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Report Date: 11/08/1999
Last Updated: 05/11/2004
Document ID: 1R77CP3Y

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