See the documentation for info on specific Saxcomm properties.

Handshaking is basically used to prevent buffer over run if the receive buffer is full then the receiver will send a wait signal to the sender so the sender does not keep sending data that has no where to go. An ok to send will be signaled when there is room in the buffer again.

Handshaking is most important at faster speeds and on slower devices. Sending data from a new pc to a really old pc at 38400 baud would most likely require handshaking to succeed.