Research On Analog I/O Unit Of Machine Tools Embedded CNC System

As the core of CNC, numerical control system is the key to determine the performance offunctionality, reliability, and cost of CNC. Embedded system has many advantages, likestrong specificity, good stabilization, high reliability and strong flexibility. Embedded systemis widely used in all types of CNC machines. Existing embedded numerical control system ofCNC usually has no auxiliary equipment control. Hydraulic lubrication and accessibility areusually done by an independent PLC. This kind of structure is both unreasonable and difficultto meet the requirement and trend of controlling the environment and the equipment.Firstly this paper introduces embedded system and its development, then analysis thestructure of CNC and its unreasonable parts. On the basis above this paper proposes a totalembedded CNC system programme which can both overcome the disadvantages of traditionalCNC and meet the needs of development. This programme treats human-machine interfaces,motion controller and I/O as network sites and constitute them as a network. So that it cancontrol CNC, auxiliary equipment, front and rear equipment and environment.This paper focuses on analog input and output modules of the programme. Analyses ofthe functions and resources of the programme and various of embedded programmes, thispaper establishes "STM32+FPGA" as the core of the system architecture. Complete analogsignal inputs and outputs(8 inputs, 8 outputs) control. The input voltage range is 0~10V andthe output voltage range is 0~5V. System uses STM32 as main chip to complete A/D and D/Aconversion and generates control signals. System uses FPGA to complete data caching andtransmission. System design of hardware circuit includes: power supply circuit, FPGA and theSTM32 peripheral circuit, isolating amplifier circuit, analog switches, sample-and-hold circuitand communication circuit. Use Altium Designer 10 to complete PCB design. On the softwaredesigns, use C language through Keil u Vision4 to finish ADC, DAC,and FSMC modulesdesign and use Verilog through Quartus II to finish FPGA modules designs. In the end, testsystem software and hardware to prove the functions and reliability of the system.