Flow Control

Flow control refers to the techniques used by computer devices to stop and restart the flow of data to and from each other. The flow control system is designed to prevent a problem known as data overrun, in which the receiving device is overrun with data faster than it can process it. Choosing a flow control method is highly recommended.

The default setting (Xon/Xoff) is a software method of flow control. In this method, two special characters (Xon and Xoff) are used to control the flow of data between the modem and the computer. The Xoff character, which stands for transmit off, is used to tell the modem to stop transmitting. When the computer is ready to receive data again, it sends the Xon character, which stands for transmit on.

The other setting is Hardware, which uses a wire in the cable to signal when to start and stop sending data. Hardware flow control is much faster than the Xon/Xoff method because it does not have the overhead necessary to manage the software commands.