Modbus RTU 通信规约
2
目 录
1 适用范围..........................................................................................................................................3
2 名词解释..........................................................................................................................................3
3 MODBUS 协议详解.....................................................................................................................3
3.1 通信传输过程 ...............................................................................................................3
3.2 通信数据字节格式......................................................................................................3
3.3 通信数据（信息）帧格式 ........................................................................................4
3.3.1
地址域
...............................................................................................................................4
3.3.2
功能码
...............................................................................................................................4
3.3.3
数据域
...............................................................................................................................4
3.3.4
错误校验（
CRC
）
.......................................................................................................5
3.4 错误信息 ........................................................................................................................5
4 功能码实例 .....................................................................................................................................6
4.1 01 功能码：读线圈输出状态....................................................................................6
4.2 02 功能码：读输入状态.............................................................................................6
4.3 03 功能码：读保持寄存器 ........................................................................................7
4.4 04 功能码：读输入寄存器 ........................................................................................7
4.5 05 功能码：写单个线圈.............................................................................................7
4.6 06 功能码：写单个保持寄存器 ...............................................................................8
4.7 15 功能码：写多个线圈.............................................................................................9
4.8 16 功能码：写多个寄存器 ........................................................................................9
5 CRC 代码 .......................................................................................................................................10
6 参考资料........................................................................................................................................11
