National Instruments VXI-USB - Manual (Page 44)

© National Instruments Corporation D-1 VXI-USB User Manual
D
Common Questions
This appendix addresses common questions you may have about using the
NI-VISA/NI-VXI software on the VXI-USB platform.
What does hot plugging mean in terms of USB?
The concept of hot plugging in USB means that you can remove and insert
USB cables without powering down your computer and devices. The USB
Plug and Play architecture is designed so that the host computer can
recognize when to load and remove the appropriate drivers.
Does it matter if I plug my VXI-USB or other USB device into any
particular USB port? For example, does it matter whether I plug a
USB device into the USB ports in my computer or into the VXI-USB in
my mainframe?
A USB device may be plugged into any port on the VXI-USB or your
computer. Doing so can change the topology of the system, which may
affect system performance in some cases. The effect may vary greatly,
depending on the system and types of devices installed.
Also, if your computer has integrated USB 2.0, you should use one of the
integrated ports rather than a USB 2.0 plug-in card if possible. Integrated
USB 2.0 ports typically offer better performance due to their tight coupling
with your motherboard and chipset. Of course, if you have the choice
between a USB 2.0 port and a USB 1.x port, always use the USB 2.0 port
even if that means you are using a plug-in card instead of an integrated port.
I need more devices than can fit in one chassis. How can I expand my
VXI-USB system?
You can add another VXI-USB to the system, but the additional chassis will
not share the same VXI bus. The recommended strategy is to use a
VXI-MXI-2, which follows the VXI-6 specification for mainframe
extension. This extends full VXI functionality across multiple mainframes,
including a common device address space and interframe triggering,
interrupts, and bus mastering. Place a VXI-MXI-2 in the same frame as the
Slot 0 VXI-USB, and another VXI-MXI-2 in Slot 0 of the next mainframe.
You can then fill up this mainframe with additional devices.