SetHandFlow Method

The SetHandFlow method sets the configuration of handshake flow control.

BOOL SetHandFlow(
  	ULONG ControlHandShake, 	// Handshake control parameter
  	ULONG FlowReplace, 	// Flow control parameter
  	ULONG XOnLimit, 	// Flow control parameter
  	ULONG XOffLimit 	// Flow control parameter
);

Parameters:

• ControlHandShake [out] : ControlHandShake is a set of flags that defines the modem lines that are used for flow control. Can be combination of the following flags:
  

  Value	Meaning	Hex
  SERIAL_DTR_CONTROL	Enables the DTR line when the device is opened and leaves it on.	0x01
  SERIAL_DTR_HANDSHAKE	Use the modem signal DTR for input flow control. For the real serial port the DTR line is cleared by the controller if the receive buffer reaches the programmed high water mark. See also description of XonLimit and XoffLimit.	0x02
  SERIAL_CTS_HANDSHAKE	Use the modem signal CTS, DCD or DSR respectively for output flow control. For the real serial port if the corresponding modem line(s) found as cleared, the controller will hold data transmission.	0x08
  SERIAL_DCD_HANDSHAKE		0x20
  SERIAL_DSR_HANDSHAKE		0x10
  SERIAL_DSR_SENSITIVITY	Ignore any character arriving when the DSR line is not set.	0x40
  SERIAL_ERROR_ABORT	If there exists an error condition the driver abort all read and writes to or from this port.	0x80000000

• FlowReplace [out] : FlowReplace is a set of flags defining flow control stuff. Can be combination of the following flags:
  

  Value	Meaning	Hex
  SERIAL_AUTO_TRANSMIT	Use the XON/XOFF protocol based flow control for output.	0x01
  SERIAL_AUTO_RECEIVE	Use the XON/XOFF protocol based flow control for input.	0x02
  SERIAL_ERROR_CHAR	If set, the ErrorChar is placed in the stream of received characters on error conditions like buffer overflow, frame errors and so on.	0x04
  SERIAL_NULL_STRIPPING	If set, the reception of a NULL character is ignored.	0x08
  SERIAL_BREAK_CHAR	If set, the BreakChar is placed in the stream of received characters when a break condition was detected.	0x10
  SERIAL_RTS_CONTROL	Enables the RTS line when the device is opened and leaves it on.	0x40
  SERIAL_RTS_HANDSHAKE	Use the modem signal RTS for input flow control.	0x80

• XOnLimit [out] : Minimum number of bytes allowed in the input buffer before flow control is activated to inhibit the sender.
• XOffLimit [out] : Maximum number of bytes allowed in the input buffer before flow control is activated to allow transmission by the sender.

Return Values : If the function succeeds, the return value is TRUE, otherwise the return value is FALSE.

Notes:

1. This method is available starting from Windows 2000 only.
2. these port settings are actual untill they are not changed by VSP AX or application, which opened virtual serial port. If these settings are changed, you get a corresponding message (in that case OnHandFlow event). Be carefull, when you are changing this parameter from VSP AX in event body, as you might get into an endless loop.