Casio IT-2000W manual

Note:

If the application specifies -1 for the cbWriteNotify parameter, the WM_COMMNOTIFY message will be sent to the specified window in the case of CV_EVENT notification or CN_TRANSMIT notification, but it will not be sent in the case of CN_RECEIVE notification. If the application specifies -1 for the cbOutQueue parameter, CV_EVENT notification or CN_RECEIVE notification will be made, but CN_TRANSMIT notification will not be made. It a time-out occurs before the number of bytes specified by the cbWriteNotify parameter is written in the input queue, a WM_COMMNOTIFY message with a set CN_RECEIVE flag will be sent. In this case, the next message will not be sent until the number of bytes in the input queue is less than the value specified by the cbWriteNotify parameter. Similarly, a WM_COMMNOTIFY message with a set CN_RECEIVE flag will be sent only if the data size of the output queue is greater than the number of bytes specified by the cbOutQueue parameter.

Note on IrDA:

There is no particular restriction on use.

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