The biggest reason for the ascendance of these two busses is the underlying PC technology where the PC goes, PC-based test follows. The PXI bus is an extension of the PCI bus, which has been around for several years. Its original purpose was to provide a high-speed bus to transfer data between the motherboard and peripheral cards. PC companies that are pushing the universal serial bus have, as one of their goals, complete elimination of add-in cards. USB is a relatively high-speed link that should allow many users to add peripherals scanners, digital cameras, and modems to their PC systems without opening the case.
Engineers can just as easily add data-acquisition peripherals with a USB port.
Schematics show two methods for connecting data-acquisition modules to the USB port of a personal computer. Simplified setup One of the biggest hassles associated with PC-based data acquisition is setting things up. You have to open up the computer, sometimes set DIP switches on the data-acquisition board, and then button it all up again. If you mess up, you have to do it all over again. Using USB makes setup a lot simpler.