USBSimple Example ( Still beginner )
USBSimple Example ( Still beginner )
- Subject: USBSimple Example ( Still beginner )
- From: Francis Derive <email@hidden>
- Date: Tue, 27 Mar 2007 21:08:14 +0200
Dear all,
In the dealWithDevice() procedure of this example, I have added the "false" case to the sequence of "if" statements only but to trace with a "printf".
When my CanoScan 8400F is plugged in with Power on - I had changed the idVendor & idProduct from the example accordingly -, the non-error of the if branches are traced in the Run Log window until happens an error ret = 0x2c5 ( kIOReturnExclusiveAccess ).
[Session started at 2007-03-27 19:36:10 +0200.] Found device 0x1103 dealWithDevice: created plugin. ret = 00000000, iodev = 0x3020f8 dealWithDevice: created a device interface. ret = 00000000, dev = 0x302100 dealWithDevice: unable to open device. ret = e00002c5
USBSimpleExample has exited with status 0.
When I have my CanoScan powered off, no traces are printed in the Run Log window- but the final main's return 0.
[Session started at 2007-03-27 21:05:34 +0200.]
USBSimpleExample has exited with status 0.
Could someone explain me what is to be understood here : The scanner can't be shared of course, and is it because it is powered on that it is already open - so that I get an error to ask for opening it a second time ?
But, switching off the power, my USBSimpleExample tool could "return 0" - with a blank Run Log : no traces.
What is the story about ?
Francis. |
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