Design Of Industrial Control Board Based On S08Microcontroller

In the modern industrial control field, the programmable logic controller (PLC) has become the key equipment of the automatic control. However, with the continuous development of the technology of computer and semiconductor, the industrial control products have been developed into the design stage of personalized and differentiated, these features mainly reflected on cost control and functional requirements etc. While the SCM system is the product of individual needs, and the SCM system is more flexible on cost control. After research and analysis found that the8-bit microcontroller always been selected as the control center in the simple control field. Therefore, the author decided to design an industrial control board based on8-bit microcontroller.First of all, the design of hardware circuit for industrial control board must be finished. The design selects S08series MCU chip designed by FREESCALE semiconductor as the master of the industrial control board. On one hand, the hardware designed special input and output processing circuits in order to preserve the control requirements of the multi-input and multi-output of traditional PLC. On another hand, taking into account the applicable fields of the application, the RS-485communication interface that can be used to implement the communication between the industrial control boards with the other controllers. Thirdly, an EEPROM and a RTC are extended by IIC bus, and the EEPROM can be used to storage the configuration parameter. At last, an SPI interface will be preserved as the extended interface for more functions.Secondly, the design of system software includes the design of the hardware drivers and the transplantation of Modbus communication protocol. The hardware drivers provide the interfaces of the controller for the upper software; a communication network is built via RS-485communication interface, and then the controller can be exchange information with external devices through the Modbus communication protocol in order to control the system centrally. In the design process of system software, it is necessary to give full consideration to the flexibility and reusability of the software, all the software will be packaged into a library file and the users only need to call each module’s flexible API functions of each module to complete development work.Meanwhile, anti-jamming measures are discussed from both hardware and software in order to improve the reliability of the system. Finally, the author designed an actual case that can be used to complete the system test. From the function point, there is no difference between the traditional PLC and the microcontroller-based industrial control board, but the cost of the microcontroller and the design of interface circuits are much lower than the PLC, and the volume will be smaller than it. So the design is very fit for the control system which has strict demands of cost and structure.