PURPOSE: To restrict the increase of a temperature at a line feed motor and thereby prevent the failure of the line feed motor by allowing the line to be fed by a continuous line feed command after the lapse of a specified time from a moment when a continuous step count setting the limits to the temperature of the line feed motor.

CONSTITUTION: The number of steps for the continuous line feed by a line feed motor 4 is counted by a line feed command sent from a host computer 1. The line is fed by continuous line feed commands after the lapse of a specified time from a moment when the number of continuous steps setting the limits to the increase of a temperature at the line feed motor 4 is reached. Subsequently, an operator can restrict the increase of a temperature at the line feed motor 4 and prevent the failure of the line feed motor, if a host computer 1 continuously sends the extremely unusual number of line feed commands.