The opinions of the CNC processing center are as follows: the reverse error (discharge) of the linear movement, including the reverse dead area of the drive site of the coordinate axis (such as servo motors, hydraulic motors, and stepping motors, etc. Comprehensive reflection of errors such as reverse gaps and elastic deformation of mechanical motion transmission. The larger the error, the lower the positioning accuracy and the repeated positioning accuracy. The detection method of reverse errors is to move a distance to the positive or reverse movement in advance within the schedule of the measured coordinate axis and stop the position as the benchmark. Then move the same distance in the opposite direction to measure the difference between the stop position and the benchmark position. Multiple determinations (generally 7 times) are performed at the middle point of near the itinerary and the three positions at both ends. Find the average value at each position, and the large value in the income average is the reverse error value.