The RTSFlowControlType property specifies the request-to-send (RTS) flow control. RTS is used to signal that data is available ...

The RTSFlowControlType property specifies the  request-to-send (RTS) flow control. RTS is used to signal that data is available for transmission. Uses of this member include:
Disable - RTS is ignored after the first RTS signal is received.
Enable - RTS is left on for the data transfer session.
Handshake - RTS is turned off if the transmission buffer is more than three-quarters full, and RTS is turned on when the buffer is less than one-half full.
Toggle - RTS is turned on if there is any data buffered for transmission.