User Manual

SR8856B User Manual http://www.sonbus.com/
Sha nghai Sonbest Industrial Co., Ltd Page9
Communication Protocol
The product uses RS485 MODBUS-RTU standard protocol format, all operation or reply commands
are hexadecimal data. The default device address is 1 when the device leaves the factory, and the module
or NON-Recorder default baud rate is 9600,8,n,1 ,but data recorder default baud rate is 115200 .
1. Read data (function code 0x03)
Inquiry frame (hexadecimal), sending example: query 1 data of 1# device, the upper computer sends
the command: 01 03 00 00 00 04 44 09 .
Address
Function Code
Start Address
Data Length
Check Code
01
03
00 00
00 04
44 09
For the correct query frame, the device will respond with data: 01 03 08 00 7C 00 00 00 00 00 00 28
10 , response format:
Address
Function
Code
Length
Data 1
Data 2
Data 3
Data 4
Check
Code
01
03
08
00 79
00 7A
00 7B
00 7C
28 10
Data description: The data in the command is hexadecimal, take data 1 as an example, 00 79 is
converted to decimal value as 121, assuming the data magnification is 100, then the real value is
121/100=1.21, Others and so on.
2. Common data address table
Configuration
Address
Register Address
Register
Description
Data Type
Value Range
40001
00 00
temperature
Read Only
0~65535
40002
00 01
temperature
Read Only
0~65535
40003
00 02
temperature
Read Only
0~65535
40004
00 03
noise
Read Only
0~65535
40101
00 64
Model Code
Read/Write
0~65535
40102
00 65
total number of
measuring points
read/write
1~20
40103
00 66
device address
read/write
1~249
40104
00 67
baud rate
read/write
0~6
40105
00 68
communication
mode
read/write
1~4
40106
00 69
protocol type
read/write
1~10
3 Read and modify device address
(1) Read or query device address
If you don't know the current device address and there is only one device on the bus, you can query
the device address through the commandFA 03 00 66 00 01 71 9E .
Device Address
Function Code
Start Address
Data Length
Check Code
FA
03
00 66
00 01
71 9E
FA means 250 is the general address, when you don't know the address, you can use 250 to get the
real device address, 00 66 is the device address register.
For the correct query command, the device will respond, for example, the response data is: 01 03 02
00 01 79 84, and its format parsing is shown in the following table:
Device Address
Function Code
Start Address
Model Code
Check Code