[KM51B90]  RS485 temperature and humidity atmospheric pressure sensor

KM51B90 KM51B90

Technical Parameters

Technical parameterParameter value
Atmospheric pressure range30~110kpa
Atmospheric pressure accuracy±0.5%
Temperature measuring range-30℃~80℃
Temperature measuring accuracy±0.5℃ @25℃
Humidity measuring range0~100%RH
Humidity accuracy±3%RH @25℃
Communication InterfaceRS485
Default baud rate9600 8 n 1
PowerDC9~24V 1A
Running temperature-30~85℃
Working humidity5%RH~90%RH

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Wiring instructions

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KM51B90 KM51B90 KM51B90

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Application solution



KM51B90 KM51B90 KM51B90 KM51B90

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
010300 0000 0305 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 LengthData 1Data 2Data 3Check Code
0103 0600 7900 7A00 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
4000100 00atmospheric pressureRead Only0~65535
4000200 01temperatureRead Only0~65535
4000300 02humidityRead Only0~65535
4010100 64Model CodeRead/Write0~65535
4010200 65 total number of measuring points read/write 1~20
4010300 66device addressread/write1~249
4010400 67baud rateread/write0~6
4010500 68communication moderead/write1~4
4010600 69protocol typeread/write1~10

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