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VXI Data Acquisition Configuration and Installation

Hardware: VXI/VME/MXI>>VXI Data Acquisition and Instrument Modules

Problem:
How do I configure and install my VXI data acquisition hardware?

Solution:

What Signal Conditioning Modules/Accessories can I use with my VXI Data Acquisition Device(s)?

Several Signal Conditioning Modules and Accessories are available. For high channel count systems, we recommend using either SCXI and/or VXI-SC modules. For lower channel counts, consider using a front panel terminal block, SCC modules, or a SC-2056 adapter board that allows you to attach additional signal conditioning accessories. The following table summarizes the various signal-conditioning options.

Option

Connection

VXI-TB-[1:2]-96

Front panel terminal block, screw terminals

TBX-96, SH96-96

DIN RAIL mount terminal block, screw terminals

SCXI-1356 (SH96-6868)

SCXI, TBX-68, SCC modules

SH96-100

SC-2056 adapter board

VXI-TB-1303

Front panel terminal block, screw terminals

VXI-SC-1000, VXI-SC-1102,
VXI-SC-1150, SCMP

VXI-TB, TBX-96, SH96-100, VXI0TB-1303, etc.


Why is my VXI MIO data acquisition device failing a resource test? Why am I unable to perform buffered analog input operations? How do I configure my Win 32 MITE based controller to use a VXI data acquisition board?

The VXI MIO DAQ modules are powerful instruments and utilize several VXI bus resources when used to perform a buffered analog input operation. The Data Acquisition Resource tests attempt to perform a buffered analog input operation and this can fail for any of the reasons listed below.

  1. Type of controller or controller configuration.
    Buffered analog input operations are only possible on MITE based controllers. Additionally, the controllers must be configured to correctly support VXI DAQ devices. The VXI DAQ resource tests will fail on non MITE based controllers (older controllers, e.g. AT-MXI-1, VXIpc5xx2xx) and will also fail on a MITE based controller that has not been configured to support VXI DAQ device

    Test and Measurement Explorer can be used to configure MITE based controllers on Win 95/98/NT platforms. This is accomplished by selecting "VXI DAQ" from the list of common hardware configuration settings for the controller(s).

    Note: You must configure all of the VXI-MXI-2 devices in order to use VXI DAQ devices in a MXI-2 system. You must also configure the PCI-MXI-2.

  2. Chassis.
    The VXI MIO modules utilize the VXI interrupt and bus arbitration lines. Many older VXI chassis required the user to jumper these signals across empty slots and so an incorrectly configured chassis may cause a problem. A chassis with a damaged VXI backplane would also prevent the VXI -DAQ devices from functioning properly.

  3. PCI BIOS (if using PCI -MXI-2)
    Some PCs may not implement revision 2.1 of the PCI specification correctly and so may not allow the MITE chip to get kernel mode access or pass interrupts to the OS. If the VXI-DAQ cards work when the PCI-MXI-2 card is in another computer, than you be fairly certain there was a BIOS problem. This might be resolved by performing a BIOS upgrade and/or by disabling a "PnP OS" or "PnP enable" option in the BIOS (the exact name and location of the option varies by vendor and may not always be available). Additionally, the PCI-MXI-2 must be installed in a PCI slot that supports PCI Bus Mastering. There may be an option to enable/disable bus mastering in the BIOS, but if there is not, then the PCI slots closest to the CPU generally support bus mastering.

    You will need to contact your computer vendor to see if any BIOS upgrades or available or if they are aware of any issues associated with using PCI bus mastering devices. You will also have to consult your PC's documentation to verify that bus mastering is supported.

  4. MXI-2 cable.
    A Bent, broken or shorted connector could cause problems. In addition, the MXI-2 cable is polarized and the end that is labeled "Connect this end to device closest to mxibus controller in this daisy chain" should be oriented toward the PCI-MXI-2.

  5. Amount of memory installed in VXI controller is not a power of two or additional memory added/removed.
    You should relaunch either VXIedit or TM explorer and reselect either the "All of System RAM" for VXI Shared RAM size or "VXI-DAQ configuration" for the controller any time that you install or remove RAM. This needs to be done even if the option was already selected.

  6. Incorrectly installed drivers.
    The VXI DAQ boards are programmed and configured using NI-DAQ, just like any other National Instruments data acquisition product. NI-DAQ uses NI-VISA and NI-VXI to communicate with the VXI DAQ boards, and so may fail if one of these layers is not installed correctly. As an example, someone might have the 32-bit version of NI-DAQ installed and the 16-bit version of NI-VISA installed. This would present a problem, as 32-bit software can not access 16-bit software.


What is the purpose of the RAM module socket on the VXI DAQ board?

A RAM module allows you to perform a continuous acquisition with non-MITE based controllers (only single point I/O would be supported otherwise) and can also improve the performance of a MITE based system. Users can have several DAQ modules all acquiring data at maximum capacity (until each module fills its 64 MB max memory) and then get the data from the RAM when the system is not busy.


What type of memory can I use?

You can use either 36 pin or 32 pin 80 ns or faster SIMMs; the parity is not important. You must install the memory in SIMM bank one first, and both memory banks must use same parity RAM.

Switch S3 used to set SIMM size. S3 is on if the SIMM size is larger than 4 MBx32.



How do I use the VXI DAQ onboard memory in my programs?

LabVIEW: All of the LabVIEW DAQ VIs can utilize the onboard memory. You can develop your applications using either the NI-DAQ functions, or the MIO instrument driver. It is recommended that you do not mix NI-DAQ and Instrument driver functions in the same application.

NI-DAQ: AI Config - Set "allocate DSP memory".

MIO Instrument Driver: Set "allocate on-board memory", Set number of scans to acquire.


LabWindows/CVI: You can develop your applications using either the EASY I/O NI-DAQ functions, or the MIO instrument driver. It is recommended that you do not mix Easy I/O and Instrument driver functions in the same application.

MIO Instrument Driver: Set "allocate on-board memory", Set number of scans to acquire

Easy I/O: Set_DAQ_Device_Info Attribute ND_VXIMIO_SET_ALLOCATE_MODE set to ND_VXIMIO_USE_ONBOARD_MEMORY_AI.

LabWindows Easy I/O Example:

    sizeOfData = numSamples * 8;

    dataBuffer = malloc(sizeOfData);

    // Configure MIO card for on-board memory and acquire waveform

    Set_DAQ_Device_Info (deviceNum, ND_VXIMIO_SET_ALLOCATE_MODE,

    ND_VXIMIO_USE_ONBOARD_MEMORY_AI);

    AIAcquireWaveforms (deviceNum, "2", numSamples, desiredRate, 5.0, -5.0,

    &actualRate, GROUP_BY_CHANNEL, dataBuffer);


Other Development Environments: You must use the MIO instrument driver in order to utilize the onboard memory. Note that you can still use NI-DAQ function calls if you do not need to use the onboard memory.




Related Links:

Attachments:


vxi_vxidaq_image.JPG - vxi_vxidaq_image.JPG

Report Date: 09/14/2006
Last Updated: 10/24/2006
Document ID: 41D72IDW

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