Technical Parameters
| Technical parameter | Parameter value |
| Brand | SONBEST |
| CH4 measuring range | 0~5000ppm |
| CH4 allow deviation | ±7% |
| CH4 Repeatability test | ±5% |
| Temperature characteristics | ±0.5%/℃ |
| Interface | RS485/4-20mA/DC0-5V |
| Power | DC9~26V/DC12~26V/DC9~26V |
| Running temperature | -30~85℃ |
| Working humidity | 5%RH~90%RH |
Product Selection
Product DesignRS485,4-20mA,DC0-5VMultiple output methods, the products are divided into the following models depending on the output method.
| Product model | output method |
| SM2130B | RS485总线 |
| SM2130M | 4-20mA |
| SM2130V5 | DC0-5V |
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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 01 84 0A .
| Address | Function Code | Start Address | Data Length | Check Code |
| 01 | 03 | 00 00 | 00 01 | 84 0A |
For the correct query frame, the device will respond with data: 01 03 02 00 79 79 A6 , response format:
| Address | Function Code | Length | Data 1 | Check Code |
| 01 | 03 | 02 | 00 79 | 79 A6 |
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 | methane | 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 |
For example, the range is 0~50ppm, the analog output is 4~20mA current signal, methane and current The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is methane range upper limit, A1 is the lower limit of the range, B2 is current output range upper limit, B1 is the lower limit, X is the currently read methane value, and C is the calculated current value. The list of commonly used values is as follows:
| current(mA) | methaneValue (ppm) | Calculation Process |
| 4 | 0.0 | (50-0)*(4-4)÷(20-4)+0 |
| 5 | 3.1 | (50-0)*(5-4)÷(20-4)+0 |
| 6 | 6.3 | (50-0)*(6-4)÷(20-4)+0 |
| 7 | 9.4 | (50-0)*(7-4)÷(20-4)+0 |
| 8 | 12.5 | (50-0)*(8-4)÷(20-4)+0 |
| 9 | 15.6 | (50-0)*(9-4)÷(20-4)+0 |
| 10 | 18.8 | (50-0)*(10-4)÷(20-4)+0 |
| 11 | 21.9 | (50-0)*(11-4)÷(20-4)+0 |
| 12 | 25.0 | (50-0)*(12-4)÷(20-4)+0 |
| 13 | 28.1 | (50-0)*(13-4)÷(20-4)+0 |
| 14 | 31.3 | (50-0)*(14-4)÷(20-4)+0 |
| 15 | 34.4 | (50-0)*(15-4)÷(20-4)+0 |
| 16 | 37.5 | (50-0)*(16-4)÷(20-4)+0 |
| 17 | 40.6 | (50-0)*(17-4)÷(20-4)+0 |
| 18 | 43.8 | (50-0)*(18-4)÷(20-4)+0 |
| 19 | 46.9 | (50-0)*(19-4)÷(20-4)+0 |
| 20 | 50.0 | (50-0)*(20-4)÷(20-4)+0 |
As shown in the above formula, when measuring 8mA, current current is 16.5ppm。
For example, the range is 0~50ppm, the analog output is 0~5V DC0-5Vvoltage signal, methane and DC0-5Vvoltage The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is methane range upper limit, A1 is the lower limit of the range, B2 is DC0-5Vvoltage output range upper limit, B1 is the lower limit, X is the currently read methane value, and C is the calculated DC0-5Vvoltage value. The list of commonly used values is as follows:
| DC0-5Vvoltage(V) | methaneValue (ppm) | Calculation Process |
| 0 | 0.0 | (50-0)*(0-0)÷(5-0)+0 |
| 1 | 10.0 | (50-0)*(1-0)÷(5-0)+0 |
| 2 | 20.0 | (50-0)*(2-0)÷(5-0)+0 |
| 3 | 30.0 | (50-0)*(3-0)÷(5-0)+0 |
| 4 | 40.0 | (50-0)*(4-0)÷(5-0)+0 |
| 5 | 50.0 | (50-0)*(5-0)÷(5-0)+0 |
As shown in the above formula, when measuring 2.5V, current DC0-5Vvoltage is 25ppm。