PXI bus numbering

[gkots]

I am new to PXI systems. My system consists of an external PC (MAX 4.4.1, LabWindows CVI 8.5, WinXP SP3), PXI-1045, PXI-8360, PXI-2532, PXI-4065, PXI-5152, PXI-6552 (x3), PXI-5404, PXI-7842R. I have attached a MAX report of my system. I have to say that the systems works fine but I have some questions that have to do with PXI Bus numbering.
1) Who is responsible for the numbering and sorting of these PCI buses?The sorting especially looks a little arbitrary. Why Bus 7, 8 are listed before Bus 4 (chassis 1045)?
2) The bus numbers without description are PCI bridges of the external PC? Because I looked at the task manager of the PC and I couldn't find some of them (bus 1, 6, 8). PC's motherboard is an Advantech AIMB-764. I have also attach the specifications of this motherboard.
3) Is this Bus numbering important? I mean,  can this numbering affect my software or anything else? For exaple, if I change PC, these Bus numbers will change? And if this happens, how can I face this?

Thank you in advance

[chris_amadasun]

Hello,

You cannot change the PXI VISA instrument descriptor for any PXI devices. However, the you will be able to use a VISA alias for these devices. Then you can export your MAX configuration file for use on another PC.

PXI is built off of the CompactPCI platform, each slot is essentially a PCI slot. When the PXI system first boots up, the BIOS on the controller enumerates all of the PCI busses and slots in the system. This enumerated information is what makes up the PXI VISA instrument descriptor. As such, this information cannot be changed.

For more details on PXI VISA instrument descriptor, please refer to KnowledgeBase 2IJ896LS. That KnowledgeBase goes into the details of how the enumeration is done and the assignment for each chassis.
The hardware description folder found by navigating to your National Instruments folder and then PXI hold the descrition for all the PXI slots and bridges.