51单片机实现的4路设备工作时间计时器，有C51源码和Proteus仿真文件，还包括VB编写的上位机数据采集程序源码，通过串行口读取设备工作时间数据。-4-way MCS51 hours timer device, a C51 source and the Proteus simulation files, including VB, PC data acquisition program source code, read through the serial port device work

51单片机上用来数据接收的用c++编写的源码。-Source code written in 51 microcontroller data reception c++

51单片机实现modbus通讯源码,电脑串口连接单片机下发指令-51 MCU modbus communication source