if(myCom!=NULL){

        myCom->close();

        myCom->setParent(NULL);

        delete myCom;

        myCom=NULL;

    }

    myCom = new Win_QextSerialPort(portData.Com,QextSerialBase::EventDriven);

如上可以在開啟時判斷是否已經建立串列埠類指標myCom，如果指標不為空，先關閉串列埠然後釋放指標，最後重新建立指標即可。

會出現close（）方法無法呼叫問題，需要將方法中

//			if (QThread::currentThread() != overlapThread)

//				overlapThread->wait();

兩句遮蔽掉，如下。

void Win_QextSerialPort::close() 

{

    LOCK_MUTEX();

    if (isOpen()) {

		flush();

		if (overlapThread->isRunning()) {

			overlapThread->stop();

//			if (QThread::currentThread() != overlapThread)

//				overlapThread->wait();

		}

        if (CloseHandle(Win_Handle))

            Win_Handle = INVALID_HANDLE_VALUE;

		_bytesToWrite = 0;

		QIODevice::close();

    }

    UNLOCK_MUTEX();

}