simply modbus - function code 04 - read input registers

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Read Input Registers (FC=04)Request

This command is requesting the content of analog input register # 30009from the slave device with address 17.

11 04 0008 0001 B298

11: The Slave Address (17 = 11 hex)04: The Function Code (read Analog Input Registers)0008: The Data Address of the first register requested. (30009-30001 = 8)0001: The total number of registers requested. (read 1 register) B298: The CRC (cyclic redundancy check) for error checking.

Response

11 04 02 000A F8F4

11: The Slave Address (17 = 11 hex)04: The Function Code (read Analog Input Registers)02: The number of data bytes to follow (1 registers x 2 bytes each = 2 bytes)000A: The contents of register 30009F8F4: The CRC (cyclic redundancy check).

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Simply Modbus - Function Code 04 - Read Input Registers http://www.simplymodbus.ca/FC04.htm

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