Patent ID: 7761620

Claim:
A communications system comprising: a host device; a communications buffer connected by a universal serial bus (USB) interface to the host device, and configuring an endpoint of a USB connection, wherein the communications buffer comprises a receive buffer for receiving and storing data sent from the host device; a control unit; an analyzing unit analyzing stored data that is stored in the receive buffer; and a forwarding unit forwarding commands that have been analyzed by the analyzing unit to an external device through the USB interface; wherein the control unit varies a size of the receive buffer in which the communications buffer stores the data sent from the host device, based on an instruction specifying whether flow control is active or inactive on data communicating between the host device and the receive buffer sent through a USB virtual serial communication driver from the host device, and a control is performed such that the receive buffer size is increased if the flow control is inactive and the receive buffer size is decreased if flow control is active.