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Read Holding Registers (FC=03)

Request

This command is requesting the content of analog output holding registers # 40108 to
 40110 from the slave device with address 17.

11 03 006B 0003 7687

11: The Slave Address (17 = 11 hex)
03: The Function Code (read Analog Output Holding Registers)
006B: The Data Address of the first register requested. (40108-40001 = 107 = 6B hex)
0003: The total number of registers requested. (read 3 registers 40108 to 40110) 
7687: The CRC (cyclic redundancy check) for error checking.

Response

11 03 06 AE41 5652 4340 49AD

11: The Slave Address (17 = 11 hex)
03: The Function Code (read Analog Output Holding Registers)
06: The number of data bytes to follow (3 registers x 2 bytes each = 6 bytes)
AE41: The contents of register 40108
5652: The contents of register 40109
4340: The contents of register 40110
49AD: The CRC (cyclic redundancy check).

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