According to control requirements, touch screen control is adopted. The input signals of PLC all come from sensors, 2 photoelectric sensors, 3 capacitive proximity switch sensors, 1 inductive proximity switch sensor, 5 manipulator motion in-place detection sensors, 4 A and B cylinder motion in-place detection sensors, a total of 15 Pcs. The output includes 3 indicator lights, 1 feed motor, 1 belt motor, 7 solenoid valves for the robot to control the cylinder movement, 4 solenoid valves for the A and B cylinder movement, a total of 16. A total of 31 I / O points are required for input and output. The following is the input / output point allocation table of the material automatic sorter PLC,