Hello all,
We are trying to communicate with a printer through USB on MAC OS X.
Basically we did followings:
1. OpenUSBPort(). Here we make: IOUSBInterfaceInterce, inPipe, and outPipe,
etc ready. CreateInterfaceAsyncEventSource(), and CFRunLoopAddSource() are
called here.
2. WriteToPort(). Here we called WritePipeAsync(intfIntf, outPipe, outBuf,
nSize, WriteCompletion, dummy), then call CFRunLoopRun(). WriteCompletion
function is called as expected. Inside WriteCompletion function, we called
CFRunLoopStop(CFRunLoopGetCurrent(). Everything goes fine.
3. ReadFromPort(). We called ReadPipeAsync(intfIntf, inPipe, inBuf, nSize,
ReadCompletion, dummy). The programming returns with noErr here. Then we
called CFRunLoopRun( ), which leads the application hangs there forever.
This results that the ReadCompletion function never got called. Inside
ReadCompletion function, we called CFRunLoopStop(CFRunLoopGetCurrent(). If
we remove the CFRunLoopRun() inside ReadFromPort(), sometimes we can get
data back, but not everytime. There is no such problem for this printer on
other OS.
4. CloseUSBPort() just does the cleanup.
Could someone help me out from the hanging up problem?
Thanks in advance.
Kane Zheng
Scanvec Amiable.
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