SetXoff Method

The SetXoff method causes transmission to act as if an XOFF character has been received.  

BOOL SetXoff(
  void  
);

Return Values   If the method succeeds, the return value is TRUE. If the port was not closed the return value is FALSE.
Remarks   This method works only when software flowcontrol (xon/xoff) operation is executed. How to execute this operation you can refer to InitString method.