METHOD OF RECONSTITUTING INSTRUCTION POSITION

摘要

Method of reconstituting instruction position in a numerical control system comprising an NC unit (11) having a path control function and a machine position correction function; a motor (15) which revolves according to an instruction from the NC unit to drive a mechanical moving part; a pulse coder (16a) which revolves in synchronism with the revolution of said motor and which generates a pulse every time, after a predetermined angle of revolution; and a counter (16b) which counts said pulse in a direction of revolution to store the machine position, and which continues to store said machine position even when the power supply is disconnected. In this method of reconstituting the instruction position, a counted value CRA of the counter (16b) at the time of returning to a reference point is set to a battery backed-up memory (11c), a counted value CA of the counter (11c) is read out every time when the power supply is closed, the reference point is imaginarily set to be a present machine position, and the machine position when the power supply is closed is set to be a target position. Under the condition where the machine is locked, the interpolation operation is carried out internally to renew the data CRA of the present machine position, the mechanical moving part is imaginarily moved from the reference point up to the present machine position when the power supply is closed (until CRA=CA), and the instruction position when the power source is closed is reconstituted using instruction data necessary for the movement.