Product

Technical Parameters

Technical parameter	Parameter value
Brand	SONBEST
CO2 range	0~5000ppm
CO2 accuracy	±100ppm
Interface	RS485/4-20mA/DC0-5V/DC0-10V
Power	DC12~24V 1A
Running temperature	-30~85℃
Working humidity	5%RH~90%RH

Product Selection

    Product DesignRS485,4-20mA,DC0-5V,DC0-10VMultiple output methods, the products are divided into the following models depending on the output method.

Product model	output method
SM1901B	RS485总线
SM1901M	4-20mA
SM1901V5	DC0-5V
SM1901V10	DC0-10V

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Why choose this product?

How to use?

Application solution

Pictures

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	carbon dioxide	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 0~5000ppm, the analog output is 4~20mA current signal, carbon dioxide and current The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is carbon dioxide 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 carbon dioxide value, and C is the calculated current value. The list of commonly used values is as follows:

current(mA)	carbon dioxideValue (ppm)	Calculation Process
4	0.0	(5000-0)*(4-4)÷(20-4)+0
5	312.5	(5000-0)*(5-4)÷(20-4)+0
6	625.0	(5000-0)*(6-4)÷(20-4)+0
7	937.5	(5000-0)*(7-4)÷(20-4)+0
8	1250.0	(5000-0)*(8-4)÷(20-4)+0
9	1562.5	(5000-0)*(9-4)÷(20-4)+0
10	1875.0	(5000-0)*(10-4)÷(20-4)+0
11	2187.5	(5000-0)*(11-4)÷(20-4)+0
12	2500.0	(5000-0)*(12-4)÷(20-4)+0
13	2812.5	(5000-0)*(13-4)÷(20-4)+0
14	3125.0	(5000-0)*(14-4)÷(20-4)+0
15	3437.5	(5000-0)*(15-4)÷(20-4)+0
16	3750.0	(5000-0)*(16-4)÷(20-4)+0
17	4062.5	(5000-0)*(17-4)÷(20-4)+0
18	4375.0	(5000-0)*(18-4)÷(20-4)+0
19	4687.5	(5000-0)*(19-4)÷(20-4)+0
20	5000.0	(5000-0)*(20-4)÷(20-4)+0

    As shown in the above formula, when measuring 8mA, current current is 1254ppm。
  For example, the range is 0~5000ppm, the analog output is 0~5V DC0-5Vvoltage signal, carbon dioxide and DC0-5Vvoltage The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is carbon dioxide 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 carbon dioxide value, and C is the calculated DC0-5Vvoltage value. The list of commonly used values is as follows:

DC0-5Vvoltage(V)	carbon dioxideValue (ppm)	Calculation Process
0	0.0	(5000-0)*(0-0)÷(5-0)+0
1	1000.0	(5000-0)*(1-0)÷(5-0)+0
2	2000.0	(5000-0)*(2-0)÷(5-0)+0
3	3000.0	(5000-0)*(3-0)÷(5-0)+0
4	4000.0	(5000-0)*(4-0)÷(5-0)+0
5	5000.0	(5000-0)*(5-0)÷(5-0)+0

    As shown in the above formula, when measuring 2.5V, current DC0-5Vvoltage is 2500ppm。
  For example, the range is 0~5000ppm, the analog output is 0~10V DC0-10Vvoltage signal, carbon dioxide and DC0-10Vvoltage The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is carbon dioxide range upper limit, A1 is the lower limit of the range, B2 is DC0-10Vvoltage output range upper limit, B1 is the lower limit, X is the currently read carbon dioxide value, and C is the calculated DC0-10Vvoltage value. The list of commonly used values is as follows:

DC0-10Vvoltage(V)	carbon dioxideValue (ppm)	Calculation Process
0	0.0	(5000-0)*(0-0)÷(10-0)+0
1	500.0	(5000-0)*(1-0)÷(10-0)+0
2	1000.0	(5000-0)*(2-0)÷(10-0)+0
3	1500.0	(5000-0)*(3-0)÷(10-0)+0
4	2000.0	(5000-0)*(4-0)÷(10-0)+0
5	2500.0	(5000-0)*(5-0)÷(10-0)+0
6	3000.0	(5000-0)*(6-0)÷(10-0)+0
7	3500.0	(5000-0)*(7-0)÷(10-0)+0
8	4000.0	(5000-0)*(8-0)÷(10-0)+0
9	4500.0	(5000-0)*(9-0)÷(10-0)+0
10	5000.0	(5000-0)*(10-0)÷(10-0)+0

    As shown in the above formula, when measuring 5V, current DC0-10Vvoltage is 2500ppm。