USB digital IO interface with software event notification when an input changes state ?

Looking for a USB interface device with several digital input/output lines. Desire something that automatically notifies software (Delphi)
by firing an event whenever an input line changes state. I prefer not to have to continuously poll the device's input lines to determine when this occurs.
Ideally the device would not require software drivers to be installed. Or if it does, then they use ActiveX and not a dll.
Steve
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Do you mean 'discrete' I/O lines? Its all digital on USB.
Walter.

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This might meet your needs and is low cost. http://www.labjack.com/labjack_u12.html Included are an ActiveX wrapper and LabVIEW VIs, besides DLL's

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