[SM3990B]  RS485 interface carbon dioxide, temperature, humidity integrated sensor

SM3990

Technical Parameters

Technical parameter Parameter value
Brand SONBEST
CO2 range 0~5000ppm
CO2 accuracy ±100ppm
Temperature measuring range -30℃~80℃
Temperature measuring accuracy ±0.5℃ @25℃
Humidity measuring range 0~100%RH
Humidity accuracy ±3%RH @25℃
Communication Interface RS485
Default baud rate 9600 8 n 1
Power DC9~24V 1A
Running temperature -30~85℃
Working humidity 5%RH~90%RH

Product Size

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Wiring instructions

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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 03 05 CB .
Address Function Code Start Address Data Length Check Code
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 , response format:
Address Function Code 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 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 carbon dioxide 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 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

 


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