Dear Tim: Thank for your reply again.You remind me that I rely too much on the Minidrivers Framework provided by Microsoft. I will try another way to solve this problem. 1) use usb's tools captureing the transmission of data content. 2) analyze these data 3) implement this process with a usb wdm driver Now it's the time to begin to work.Maybe we should discuss later. good bye.Thank all of you again! best wishes suhetao ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/