I hope your development is going well.
Our USB powered devices such as the 3224 and 3424 source their power from the USB ports. They will draw upto 500mA on startup. Powered USB hubs provide both a number of ports and power for usb devices. If you pull the power from a powered hub, the switiching side will still work but any connected device will run on severely reduced power. Input devices may survive this but powered devices, such as our scopes, will not.
The general rule for USB devices is give them as much power as they require. The USB architecture will control this automatically. Use powered hubs with power supplies wherever possibly.
Michael - Tech Support
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