EscapeCommFunctionThe EscapeCommFunction function directs a specified communications device to perform an extended function. BOOL EscapeCommFunction( HANDLE hFile, // handle to communications device DWORD dwFunc // extended function to perform );
Parameters hFile Handle to the communications device. The CreateFile function returns this handle. dwFunc Specifies the code of the extended function to perform. This parameter can be one of the following values: Value Meaning CLRDTR Clears the DTR (data-terminal-ready) signal. CLRRTS Clears the RTS (request-to-send) signal. SETDTR Sends the DTR (data-terminal-ready) signal. SETRTS Sends the RTS (request-to-send) signal. SETXOFF Causes transmission to act as if an XOFF character has been received. SETXON Causes transmission to act as if an XON character has been received. SETBREAK Suspends character transmission and places the transmission line in a break state until the ClearCommBreak function is called (or EscapeCommFunction is called with the CLRBREAK extended function code). The SETBREAK extended function code is identical to the SetCommBreak function. Note that this extended function does not flush data that has not been transmitted. CLRBREAK Restores character transmission and places the transmission line in a nonbreak state. The CLRBREAK extended function code is identical to the ClearCommBreak function. Return Values If the function succeeds, the return value is nonzero.If the function fails, the return value is zero. To get extended error information, call GetLastError. Res Windows CE: Windows CE supports the following additional flags for the dwFunc parameter: SETIR Sets the serial port in IR mode. CLRIR Sets port into normal serial mode.
HANDLE hFile, // handle to communications device
DWORD dwFunc // extended function to perform
);
Parameters
hFile
Handle to the communications device. The CreateFile function returns this handle.
dwFunc
Specifies the code of the extended function to perform. This parameter can be one of the following values: Value Meaning
CLRDTR Clears the DTR (data-terminal-ready) signal.
CLRRTS Clears the RTS (request-to-send) signal.
SETDTR Sends the DTR (data-terminal-ready) signal.
SETRTS Sends the RTS (request-to-send) signal.
SETXOFF Causes transmission to act as if an XOFF character has been received.
SETXON Causes transmission to act as if an XON character has been received.
SETBREAK Suspends character transmission and places the transmission line in a break state until the ClearCommBreak function is called (or EscapeCommFunction is called with the CLRBREAK extended function code). The SETBREAK extended function code is identical to the SetCommBreak function. Note that this extended function does not flush data that has not been transmitted.
CLRBREAK Restores character transmission and places the transmission line in a nonbreak state. The CLRBREAK extended function code is identical to the ClearCommBreak function.
Return Values
If the function succeeds, the return value is nonzero.If the function fails, the return value is zero. To get extended error information, call GetLastError. Res
Windows CE: Windows CE supports the following additional flags for the dwFunc parameter: SETIR
Sets the serial port in IR mode.
CLRIR
Sets port into normal serial mode.