程序包括一组子程序和中断程序，通过S7-200自由端口功能来产生从Modbus RTU. 它支持下列Modbus功能：----1.读输出(线圈)----2.读输入(触点)----3.读保持寄存器(V.. -includes a subroutine and the interruption procedure for the adoption of the S7-200 free port functions to generate from the Modbus RTU. It support