改进型RS485模块在库房环境监控中的应用  

Application of improved RS485 module in environment-monitor for warehouse

作　　者：杨卫东[1] 张国平[1] 徐洪波[1] 

机构地区：[1]华中师范大学物理科学与技术学院,武汉430079

出　　处：《电子测量技术》2016年第3期154-156,161,共4页Electronic Measurement Technology

基　　金：华中师范大学中央高校基本科研业务费项目资助(No.CCNU14A02005)

摘　　要：设计了一种应用于库房环境监控系统中的光耦隔离型全自动收发RS485模块。利用光耦PC817对TTL信号的隔离性和TVS管SMBJ 6.8V的防浪涌特性,在原有RS485电路上进行了信号隔离,并在此基础上采用由SN74LVC1G14施密特触发器和电阻电容构成的CMOS反相电路减小信号电平转换的延时。Multisim仿真和实际应用结果表明当波特率为9600kbps时,TTL信号和485信号可以实现自动转换并且是零延时,系统通过该模块也能无差错的采集传感器的数据,从而大大提高了库房环境监控系统中数据传输的实时性和可靠性。An opticalcoupler-isolated and automatically transmitted and received RS485 module is designed for system of environment-monitor for warehouse.The isolation to TTL signal of opticalcoupler PC817 and transient voltage suppressor of TVS Diode are used to separate the system from outside signal.Then the CMOS inverter which consists of Schmidt trigger SN74LVC1G14 and RC circuit can largely reduce the delay during the signal conversion.Simulation of Multisim software and the results of actually application demonstrate that not only the TTL and 485 signal can be automatically converted to each other without any delay,but also the system can accurately receive the data from sensors.Aboveall,the module can greatly improve the reliability and real-time of data transmission in the system of environment-monitor for warehouse.

关 键 词：库房环境监控系统 RS485 自动收发 光耦隔离 

分 类 号：TP368.1[自动化与计算机技术—计算机系统结构]