说明：  不借助其它底层Modbus控件，直接操作底层通讯代码，实现Modbus读写“保持寄存器”数据，支持串口通讯、TCP通讯两种方式。代码只作演示，可做进一步封装，也可稍作修改，用于非标准的Modbus通讯。本代码使用了一个第三方控件SPComm，开发测试环境为Delphi7+Win7，我一直想摆脱Modbus控件(MBAXP Modbus Master ActiveX Control )，最近自己开发了这个DEMO，分享给大家。
(Without other underlying Modbus controls, the direct operation of the underlying communication code, the realization of Modbus read and write, "keep register" data, support for serial communication, TCP communication two ways. The code is for demonstration only, can be further encapsulated, and can be modified slightly for nonstandard Modbus communications. This code uses a third party control SPComm, development test environment for Delphi7+Win7, I always want to get rid of Modbus control (MBAXP Modbus Master ActiveX Control ) recently developed this DEMO and shared it with you.)