Development Of Remote Redundancy Process Control System Based On Modbus And ZigBee

At present, almost all gas monitoring systems are PLC control systems, while the connection between the field devices and the controllers is one-to-one, so this system has shortcomings, such as high cost, complicated routing, difficult to circuit debugging and maintenance and so on. Therefore, this article designed a remote control system module, which can manage the data of the field devices centrally and enhance the reliability of the system through the communication redundancy.The system consists of two types of modules, one is redundant communication terminal module, the other one is the redundant communication gateway module based on the Modbus and ZigBee protocol. The power supply module, communication module, signal input and output module all have a certain level of isolation and lightning protection, and it has battery backup function. The STM32F10series of ARM was used as the microprocessor and the CC2530was used as the wireless communicaton conntroller. The uC/OS-II real-time operating system and the Modbus protocol stack were cut and transplant. The IAR7.60A and Keil uVision4were used as the compile software of developing the ZigBee and the Modbus. The design of the hardware and software of the system were introduced in detail. The hardware design included the processes such as the design of the circuit diagram and schematic diagram, the selection of electrical components, the production of PCB and so on. The software design included the details such as the introduction of the principle and application of the Modbus and the ZigBee protocol stack and the transplantation, the introduction of the uC/OS-Ⅱ real-time operating system and transplantation, the software design of the terminal module, the software design of the ZigBee protocol remote communication, the software design of gateway module and so on. At last, the ModScan32, which is a kind of Modbus protocol debugging assistant, was used to test the function of the system module.This system has the following characteristics:first, it can meet the basical needs of gas monitoring system, namely to the operation of the digital and analog; second, through the ZigBee wireless communication redundancy, it can improve the reliability of the system; third, compared with the PLC control system, it can greatly reduce the cost.The terminal module support redundant communication based on Modbus protocol and ZigBee protocol, while the gateway module can realize the switch between the two types of protocol, Which has a certain value to the research of wired and wireless redundant communication.