51单片机和MCGS的工控机modbus通信程序，包括的上位机程序，以及51单片机的程序，适合初学者更好的理解和使用modbus协议通信-51 And MCGS IPC modbus communications procedures, including the PC program, as well as 51 single program, suitable for beginners to better understand and use modbus protocol communi