说明：  本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 存储器).----4.读输入寄存器----5.写单路输出----6.写单路保持寄存器----15.写多路输出----16.写多路保持寄存器
(this includes a subroutine and the interruption procedure for the adoption of the S7-200 free port functions to generate from the Modbus RTU. It supports the following functions : a Modbus. Reading output (2) coil. Reading input (contact)---- 3. Reading maintain registers (V memory ).---- 4. Reading input register---- 5. write single-output---- 6. write to maintain the single-route Register---- 15. write multiple output---- 16. write multiple maintain registers)