Three-axis motion control system based on PLC unit

The invention discloses a three-axis motion control system based on a PLC unit, and the system comprises the steps: an upper computer sets control parameters of three-axis motion, and transmits the control parameters to the PLC unit; a Z-axis control program is set in the PLC unit; an X-axis and Y-axis linkage control program is set in a positioning control unit; a two-axis linkage control program of the positioning control unit is further provided with an m code used for generating a Z-axis driving instruction; the PLC unit sends control parameters of an X-axis sliding table and a Y-axis sliding table to the positioning control unit, the positioning control unit executes the two-axis linkage control program, controls movement of the X-axis sliding table and the Y-axis sliding table in a linkage mode, executes m codes in the two-axis linkage control program, generates a Z-axis driving instruction and sends the Z-axis driving instruction to the PLC unit, and the PLC unit receives the Z-axis driving instruction