Determine the Number and Range of PCI/PCIe Root Bus Devices

Updated Dec 22, 2023



  • PXI Chassis
  • PXIe-8381
  • PCIe-8381
  • PXIe-8384

  • I have a PCI/PCIe system and I want to know the restrictions that can't be fixed using the NI MXI-Express BIOS Compatibility Software.
  • I want to know the number and range of my PCI/PCIe Root Bus Devices.
  • How can I determine if my computer's PCI/PCI Express bus has limitations that cannot be corrected by the NI MXI-Express BIOS Compatibility Software?

Application Usage: 

  1. Download and run the MXIeBusDetect.exe application attached at the bottom of this article.
Note: Only use MXIeBusDetect_32bit.exe on 32-bit Windows systems, and only use MXIeBusDetect_64bit.exe on 64-bit Windows systems.
  1. Look for root bus devices with Bus Number Range: [0, ff] and Status: Device is running
A full (non-limited) range of bus numbers will display as "[0, ff]". If the bus number range is not "[0, ff]", this indicates the motherboard has a limited number of buses to work with, and therefore may not be MXI-compatible.

An example of a system with limited range is shown below.

You might see phantom device status message, as shown below. These can be ignored. 

  1. Press Enter to terminate the program.

Save Information to File

  1. To save this information to a file, run the executable from the command prompt, piping the information to a text file.
For example, type: MXIeBusDetect_32bit.exe > out.txt


  1. Press Enter to execute the command, then press Enter again to terminate the program. The information will be saved as out.txt or as your desired output filename.

Additional Information

MXI-Express BIOS Compatibility Software works around common BIOS limitations; however, not all possible limitations can be managed. Among the configurations that MXI-Express BIOS Compatibility Software cannot compensate for, some can be detected in advance (prior to installation of software), including:

  • The presence of multiple PCI/PCI Express root bus devices, which adds complexity to the system.
  • A low maximum limit on the bus number range set by the BIOS, which limits the amount of hardware that can be attached to the system.


The installer for MXI-Express BIOS Compatibility Software checks for these issues and alerts detection through pop-up messages. In the case of multiple root bus devices, installation is prevented.


Note: MXI-Express BIOS Compatibility Software versions 1.4 and newer do support multi-root bus systems, though the MXIeBusDetect utility may suggest otherwise when run on certain systems. An alternative to detect these issues in advance is to use a stand-alone application, the MXI Express Compatibility Root Bus Detection Utility, which is attached to this article. It will provide information about the system's PCI/PCI Express root bus devices and the implications of any detected issues. You should only use the version of the MXIeBusDetect executable that corresponds to your version of Windows. 32-bit versions of Windows should use the MXIeBusDetect_32bit.exe utility, and 64-bit versions of Windows should use the MXIeBusDetect_64bit.exe utility.