Thermo Scientific Omni FTIR Multi Gas CEMS Instruction Manual page 212

Modbus Protocol
Function Codes
B-4 Omni FTIR Multi Gas CEMS Instruction Manual
Request
Function Code
Starting Address
Quantity of Registers
Response
Function Code
Byte Count
Register Value
*N = Quantity of Registers
Here is an example of a request and response to read registers 9–12:
Request
Field Name
Function
Starting Address Hi
Starting Address Lo
No. of Registers Hi
No. of Registers Lo
Response
Field Name
Function
Byte Count
Register Value Hi (9)
Register Value Lo (9)
Register Value Hi (10)
Register Value Lo (10)
Register Value Hi (11)
Register Value Lo (11)
Register Value Hi (12)
Register Value Lo (12)
The contents of register 9 are shown as the two byte values of 0x02 0x2B.
Then contents of registers 10–12 are 0x00 0x00, 0x00 0x64 and 0x00
0x64, respectively.
1 Byte 0x03
2 Bytes 0x0000 to maximum allowed by instrument
2 Bytes 1 to maximum allowed by instrument
1 Byte 0x03
1 Byte 2 x N*
N* x 2 Bytes N = N or N+1
(Hex)
0x03
0x00
0x08
0x00
0x04
(Hex)
0x03
0x06
0x02
0x2B
0x00
0x00
0x00
0x64
0x00
0x64
Thermo Fisher Scientific