Modbus 主站串口通信程序，主要可以实现与Modbus 从站设备的连接，本程序主要用于与ABB变频器的连接，可以控制电机的起停与控制。-Modbus master serial communication procedures, can be achieved mainly with Modbus slave devices connected, this program is mainly used for connecting ABB drives can be controlled with the start-stop control of the motor.