ICON ProCon C700 Series Operating Manual page 25

C700 | C720 Series Operating Manual
The following illustrates the request frame and response frame with the read and hold register 108-110 as an example. (The contents of
register 108 are read-only, with two-byte values of 0X022B, and the contents of register 109-110 are 0X0000 and 0X0064)
Request Frame
Number Systems
Function code
Start address (high byte)
Start address (low byte)
Number of Read Registers (High Bytes)
Number of Read Registers (Low Bytes)
Figure 10: Examples of read and hold register request and response frames
MODBUS function code 0x10: write multiple registers
This function code is used to write continuous registers to remote devices (1... 123 registers) block that specifies the value of the registers
written in the request data frame. Data is packaged in two bytes per register. Response frame return function code, start address and
number of registers written.
Request:
Function Code
Start Address
Number of Input Registers
Number of Bytes
Register Values
N = Register number
Figure 11: Write multiple register request frames
Response:
Function Code
Start Address
Number of Input Registers
Number of Bytes
Register Values
N = Register number
Figure 12: Write multiple register response frames
(Hexadecimal)
0x03
0x00
0x6B
0x00
0x00
1 byte 0x03
2 bytes 0x0000....0xfffff
2 bytes 1...125
1 byte Nx2
N×2 bytes Value
1 byte 0x03
2 bytes 0x0000....0xfffff
2 bytes 1...125
1 byte Nx2
N×2 bytes Value
Response Frame
Function code
Register Value (High Bytes) (108)
Register Value (Low Bytes)(108)
Register Value (High Bytes) (109)
Register Value (Low Bytes) (109)
Register Value (High Bytes)(110)
Register Value (High Bytes)(110)
Register Value (Low Bytes) (110)
Function code
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(Hexadecimal)
0x03
0x06
0x02
0x2B
0x00
0x00
0x00
0x64