Physical Memory Allocation Using VISA Primary Software: LabWindows/CVI Development Systems>>Full Development SystemPrimary Software Version: 8.0 Primary Software Fixed Version: N/A Secondary Software: N/A Hardware: GPIB>>Plug-in Controllers>>PCI-GPIB
Problem: I'm using CVI and am trying to allocate/access memory inside my PC and then allow my PCI/VISA device to write data to that memory. However, I can't get the physical address of the SDRAM inside my PC to give to my VISA device so that it can write data there over the PCI bus. How can I do this? Solution: You will need to have two VISA session open to accomplish this. PXI::MEMACC is a generic resource name for the computer your are using. If you use PXI::MEMACC as a resource name, this will target the PC's memory. Open two sessions: one to your device and one to PXI::MEMACC . You can then use viMemAlloc with PXI::MEMACC. This allocates a physical chunk of RAM and returns the physical address. You can then give this address to your VISA device in your other open session. In addition, you could also use viMapAddress to map from the physical to the logical address on your PC. Related Links: KnowledgeBase 3KDDNHPC: How Many Devices Can NI VISA Support? Attachments:
Report Date: 08/11/2006 Last Updated: 09/09/2006 Document ID: 40A9KKD2 |
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