PURPOSE: To evade the stoppage of a data reception due to a time-out at a host side by judging whether a space area is left or not in the data reception and performing the data reception, when a data is received beyond a regulated area and after that, by every prescribed bytes at a regulated time interval.

CONSTITUTION: When the space area in the data is calculated and it is reduced below half, the interruption of the data reception caused by the sending of the data is prohibited and a timer (low speed reception timer) which generates the interruption with a regulated time interval is started. By the interruption of the timer with a regulated time interval, it is decided whether a request for the reception exists or not and when the reception request for the data exists, the data is received and is stored. By cutting the data reception time with a regulated time interval shorter than a time decided as a device time-out, the device time-out is prevented.