Why Do PXI Devices Show Up As Unknown/Empty Under Slot View For My Chassis?

Updated Feb 26, 2018

Reported In


  • PXI Chassis
  • PXI-1036

Issue Details

When I click on my PXI Chassis under the PXI System tree in MAX and expand it, only my controller is listed in Slot 1 and the rest of the slots are listed as unknown/empty. The devices in my chassis show up correctly in the tree view underneath the PXI Chassis and appear to be working properly, except that I haven't been able to send any signals across the PXI trigger lines. What is going on and how can I fix this?


There are four main reasons that all or some of your devices will be listed as Unknown/Empty in the Slot View for your PXI Chassis. These are some steps to possibly fix this:
  1. Verify the Hardware Driver Supports this Feature
    According to the PXI specifications, every PXI controller must support VISA, but not every driver of PXI boards must support VISA. This means that you will only be able to find the slot where PXI boards are installed using this method if, and only if, their driver supports VISA and their PXI VISA Resource Name uses the PCI Bus Number and PCI Device Number. Currently, the drivers for National Instruments' Data Acquisition boards, Modular Instrument boards, and Switch boards do support the PXI VISA Resource Names. See the Programmatic PXI Slot Detection for more information on detecting devices in PXI slots.
  2. You Need to Have the Latest Version of NI-VISA and Drivers for the PXI Cards Installed
    NI-VISA and other drivers are the software that identifies the devices in your chassis and lists them under the PXI System entry. If you don't have NI-VISA or some of the drivers installed, then your devices will show up as Unknown/Empty in MAX. Make sure you have the latest version of NI-VISA and the other drivers for your Operating System installed to correctly identify your devices.
  3. You Must Identify Your PXI Controller and Chassis Correctly
    If you don't identify your PXI controller or chassis correctly, then the wrong PXISYS.INI file will be copied to your windows directory (i.e. C:\Windows\pxisys.ini or C:\WinNT\pxisys.ini), and the devices in your chassis will not be detected properly in the Slot View for your chassis. You must make sure that you have identified your PXI Controller and Chassis correctly under the PXI system. View Configuring the PXI System Entry in MAX 3.x for more details on identifying your PXI system in MAX.
  4. Make Sure That You Have Privileges to Modify PXISYS.INI
    When you identify your PXI controller and chassis in MAX, a new PXISYS.INI file is copied to your Windows directory. If MAX shows that you have identified your system correctly and the devices are still not listed in the slot view, than it may be that MAX was unable to update the PXISYS.INI file.
  • Make sure that your windows account has privileges to modify files in the windows directory. The easiest way to ensure that you have privileges to modify files in this directory is by logging into your system as an administrator. You can right-click on the windows directory and view the security settings to see which users have privileges to modify files in the directory.
  • Make sure that the PXISYS.INI file is not read only or write protected. You can do this by right clicking on the PXISYS.INI file in the Windows directory and then view the properties for the file to see if it is read only.

If you have verified that the PXISYS.INI file is write enabled (i.e. not read only), and you still can't see your devices in the slot view, then search your computer for the PXISYS.INI file. If the file exists anywhere other than the Windows or WinNT folder, than delete that instance of the file. If this still doesn't solve the problem, than contact National Instruments technical support for assistance: http://ni.com/support.


Not Helpful