Communications device, and communications method for enabling reception of real-time execution commands when a receive buffer is full

摘要

A communications buffer and control unit that configure a USB connection endpoint are provided connected by a USB bus to a host device. The control unit changes the receive buffer size of a receive buffer where the communications buffer stores receive data, based on an instruction that is sent from the host device side through USB virtual serial communication, to enable the reception of real-time execution commands by the communications device. This enables the reception of real-time execution commands when the receive buffer on the communications device side is in a buffer-full state in data communications between a host device and a communications device.