Numerical control apparatus

A numerical control apparatus numerically controlling a motion mechanism unit of a machine tool, comprising:

• a program storage storing an NC program constituted by a plurality of blocks describing NC codes;
• a display device configured to display at least the NC program in characters;
• an automatic-operation control unit configured to execute the NC program stored in the program storage to operate the motion mechanism unit under numerical control;
• a suspending operation unit configured to suspend execution of the NC program by the automatic-operation control unit during the execution of the NC program and then resume the execution of the NC program;
• and
• a program manipulation unit configured to, when processing in the automatic-operation control unit is suspended by the suspending operation unit, with respect to the NC program under execution displayed on the display device, enable manipulation of character display on the display device with a displayed character designated or enable editing of the NC program, wherein:
• the numerical control apparatus includes an automatic-operation monitoring unit configured to:
• monitor an execution state of the automatic-operation control unit;
• at a time of resumption of the execution of the NC program after suspension of the execution of the NC program by the suspending operation unit, check whether a resumption block containing a character designated in the program manipulation unit immediately before the resumption is a preset resumable block or not;
• when the resumption block is the resumable block, resume the processing in the automatic-operation control unit from the resumption block;
• and when the resumption block is not the resumable block, halt the processing in the automatic-operation control unit.