NI USB 6501 24-ch DIO Performance Questions

[Phillip Brooks]

A quick search on these forums for '6501 change detection' led me to these items: Thread:<a href="http://forums.ni.com/ni/board/message?board.id=70&amp;message.id=4798&amp;query.id=85325#M4798" target="_blank">
USB 6501 C# Event Acquisition</a> Which had a link to this document identifying devices supporting change detection:<a href="http://digital.ni.com/public.nsf/websearch/8914FA5E30971E0C86256FEF005760FF?OpenDocument" target="_blank">http://digital.ni.com/public.nsf/websearch/8914FA5E30971E0C86256FEF005760FF?OpenDocument</a>

[Phillip Brooks]

I believe that the second link suggests that you CAN do what you would like, but only with the non-bus powered 'high performance' USB devices.
The USB-6221 has 24 digital I/O lines plus analog ports, but it costs about 10 times as much as the 6501!
I did find this thread that indicates that it is possible with th 6221, but the original poster was having problems with change detection.
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