The origin of the CNC machine tool is the reference point adjusted by the machine tool manufacturer. The position of the specific machine tool origin is set by the machine tool manufacturer. The CNC system determines the specific position of the machine tool origin by returning the machine tool reference point, so as to establish a correct machine tool coordinate system. This is the function of the CNC machine tool returning to the machine tool reference point.This is the function of the CNC machine tool returning to the machine tool reference point.

　　When the position detection device of the CNC machine tool is an absolute encoder, the system is powered by the encoder battery after the power is turned off, and the position change of the machine tool is remembered. When the system is powered on, the system exchanges data with the position detection device and refreshes the data. Make the coordinate value of the machine tool coordinate system consistent with the actual position of the machine tool. Therefore, when the position detection device is an absolute encoder, the machine tool does not need to return to the machine reference point when the machine is turned on. If the position detection device is an incremental encoder, because the coordinate value stored by the system is the position before the machine is powered off, it may be the actual position of the machine Inconsistent, so the CNC machine tool of the incremental encoder position detection device must be operated at the machine tool reference point.

　　The relative coordinate value refers to the incremental coordinate value (the coordinate offset value of each axis is 0) of the machine tool reference point moving from the machine tool origin to the machine tool reference point in the coordinate system with the machine tool origin as the coordinate origin; the absolute coordinate value refers to In the coordinate system where the machine tool origin is the coordinate origin, the absolute value of the machine tool reference point in this coordinate system (the coordinate offset value of each axis is 0). The machine coordinate value refers to the absolute coordinate value of the machine tool reference point in the coordinate system with the machine tool reference point as the coordinate origin. Of course, the definition of the coordinate system of different machine tool manufacturers is different, and the actual application should be operated according to the machine tool manual of the machine tool manufacturer.