Icon Process Controls ProCon DO3000-C Series Quick Start Manual page 21

ProCon — DO3000-C Series
®
Dissolved Oxygen Controller
Response:
Function Code
Number of bytes
Register Values
N = Register Number
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)
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 Mul tiple 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
25-0671 © Icon Process Controls Ltd.
Figure 9 : Read and hold register response frame
Request Frame
(Hexadecimal)
0x03
0x00
0x6B
0x00
0x03
Fig.11 : Write Multiple Register Request Frames
1 byte
2 bytes
Nx2 byte
Number Systems
Function Code
Byte Count
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 (Low Bytes) (110)
1 byte
2 byte
2 byte
1 byte
N x 2 bytes
0x03
Nx2
1...125
Response Frame
(Hexadecimal)
0x2B
0x00
0x00
0x00
0x10
2 byte
2 byte
1 byte
N x 2 bytes
*N = Register Number
0x03
0x06
0x02
0x64
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