Modbus Rtu Register Listing - ECD DO82 Instructional Manual

C. MODBUS RTU R
EGISTER
03 (0x03) Read Holding Registers
This function code is used to read the contents of a contiguous block of holding registers in a remote device. The Request
Protocol Data Unit specifies the starting register address and the number of registers. In the Protocol Data unit Registers
are addressed starting at zero. Therefore registers numbered 1-16 are address as 0-15.
The register data in the response message are packed as to byte per register, with the binary contents right justified
within each byte. For each register, the first byte contains the high order bits and the second contains the low order
bits.
Request
Modbus ID (Slave Address)
Function code
Starting Address
Quantity of Registers
CRC
Request
Modbus ID (Slave Address)
Function code
Byte Count
Register Value(s)
CRC
*N = Quantity of Registers
Error
Modbus ID (Slave Address)
Error Code
Exception Code
CRC
06 (0x06) Write Single Register
This function code is used to write a single holding register in a remote device. The Request Protocol Data Unit specifies
the address of the register to be written. Registers are addressed starting at zero. Therefore register number 1 is
addressed as 0. The normal response is an echo of the request, returned after the register contents have been written.
Request
Modbus ID (Slave Address)
Function code
Register Address
Register Value
CRC
Response
Modbus ID (Slave Address)
Function code
Register Address
Register Value
CRC
*N = Quantity of Registers
HYDRA-DS NO -N
3
L
ISTING
1 Byte 1 to 247 (0x01 to 0xF7)
1 Byte 0x03
2 Bytes 0x0000 to 0xFFFF
2 Bytes 1 to 125 (0x01 to 0x7D)
2 Bytes calculated
1 Byte 1 to 247 (0x01 to oxF7)
1 Byte 0x03
1 Byte 2 x N*
*N x2 Bytes
2 Bytes calculated
1 Byte 1 to 247 (0x01 to 0xF7)
1 Byte 0x86
1 Byte 01, 02, 03, or 04
2 Bytes calculated
1 Byte 1 to 247 (0x01 to 0xF7)
1 Byte 0x06
2 Bytes 0x0000 to 0xFFFF
2 Bytes 0x0000 to 0xFFFF
2 Bytes calculated
1 Byte 1 to 247 (0x01 to 0xF7)
1 Byte 0x06
2 Bytes 0x0000 to 0xFFFF
2 Bytes 0x0000 to 0xFFFF
2 Bytes calculated
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