Handshaking

This property sets and returns the hardware handshaking protocol.

Syntax

object.Handshaking [= value]

Parameters

object

Object expression that evaluates to a Comm control.

value

Integer expression that specifies the handshaking protocol. The following table shows the settings for value.

Constant	Value	Description
comNone	0 (default)	No handshaking
comXonXoff	1	XON/XOFF handshaking
comRTS	2	Request To Send/Clear To Send (RTS/CTS) handshaking
comRTSXonXoff	3	Both Request To Send (RTS) and XON/XOFF handshaking

Remarks

Handshaking refers to the internal communications protocol by which data is transferred from the hardware port to the receive buffer. When a character of data arrives at the serial port, the communications device has to move it into the receive buffer so that your application can read it. If there is no receive buffer and your application is expected to read every character directly from the hardware, you will probably lose data because the characters can arrive very quickly.

A handshaking protocol ensures that data is not lost due to a buffer overrun, where data arrives at the port too quickly for the communications device to move the data into the receive buffer.