SONBEST SM3691B, User Manual

Page: 2 / 4

SM3691B Us er Ma nual
http://www.sonbus.com/
Sha nghai Son
best Industrial Co., Ltd Page2
In the case of broken wires, wire the wires as shown in the figure. If the product itself has no leads, the
core color is for reference.
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 is shipped, the default baud rate is
9600, 8, n, 1
1. Read Data (Function id 0x03)
Inquiry frame (hexadecimal), sending example: Query 1# device 1 data, the host computer sends the
command:01 03 00 00 00 03 05 CB .
Device ID Function id Start Address Data Length CRC16
01 03 00 00 00 03 05 CB
For the correct query frame, the device will respond with data:01 03 06 00 7B 00 00 00 00 C5 7F , the
response format is parsed as follows:
Device ID Function id Data Length Data 1 Data 2 Data 3 Check Code
01 03 06 00 79 00 7A 00 7B C5 7F
Data Description: The data in the command is hexadecimal. Take data 1 as an example. 00 79 is
converted to a decimal value of 121. If the data magnification is 100, the actual value is 121/100=1.21.
Others and so on.
2. Data Address Table
Address Start Address Description Data type Value range
40001 00 00 soil temperature Read Only 0~65535
40002 00 01 temperature Read Only 0~65535
40003 00 02 humidity Read Only 0~65535
40101 00 64 model code read/write 0~65535
40102 00 65 total points read/write 1~20
40103 00 66 Device ID read/write 1~249
40104 00 67 baud rate read/write 0~6
40105 00 68 mode read/write 1~4
40106 00 69 protocol 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 ca n use the
command FA 03 00 64 00 02 90 5F Query device address.
Device ID Function id Start Address Data Length CRC16
FA 03 00 64 00 02 90 5F
FA is 250 for the general address. When you don't know the address, you can use 250 to get the real
device address, 00 64 is the device model register.
For the correct query command, the device will respond, for example the response data is: 01 03 02
07 12 3A 79, the format of which is as shown in the following table:
Device ID Function id Start Address Model Code CRC16
01 03 02 55 3C 00 01 3A 79
Response should be in the data, the first byte 01 indicates that the real address of the current device is,
55 3C converted to decimal 20182 indicates that the current device main model is 21820, the last two bytes
00 01 Indicates that the device has a status quantity.