Product

Technical Parameters

Technical parameter	Parameter value
Brand	SONBEST
Temperature measuring range	-30℃~80℃
Temperature measuring accuracy	±0.5℃ @25℃
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
SM1800B	RS485总线
SM1800M	4-20mA
SM1800V5	DC0-5V
SM1800V10	DC0-10V

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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	temperature	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 -30~80℃, the analog output is 4~20mA current signal, temperature and current The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is temperature 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 temperature value, and C is the calculated current value. The list of commonly used values is as follows:

current(mA)	temperatureValue (℃)	Calculation Process
4	-30	(80-(-30))*(4-4)÷(20-4)+-30
5	-23.125	(80-(-30))*(5-4)÷(20-4)+-30
6	-16.25	(80-(-30))*(6-4)÷(20-4)+-30
7	-9.375	(80-(-30))*(7-4)÷(20-4)+-30
8	-2.5	(80-(-30))*(8-4)÷(20-4)+-30
9	4.375	(80-(-30))*(9-4)÷(20-4)+-30
10	11.25	(80-(-30))*(10-4)÷(20-4)+-30
11	18.125	(80-(-30))*(11-4)÷(20-4)+-30
12	25	(80-(-30))*(12-4)÷(20-4)+-30
13	31.875	(80-(-30))*(13-4)÷(20-4)+-30
14	38.75	(80-(-30))*(14-4)÷(20-4)+-30
15	45.625	(80-(-30))*(15-4)÷(20-4)+-30
16	52.5	(80-(-30))*(16-4)÷(20-4)+-30
17	59.375	(80-(-30))*(17-4)÷(20-4)+-30
18	66.25	(80-(-30))*(18-4)÷(20-4)+-30
19	73.125	(80-(-30))*(19-4)÷(20-4)+-30
20	80	(80-(-30))*(20-4)÷(20-4)+-30

    As shown in the above formula, when measuring 8mA, current current is 31.5℃。
  For example, the range is -30~80℃, the analog output is 0~5V DC0-5Vvoltage signal, temperature and DC0-5Vvoltage The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is temperature 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 temperature value, and C is the calculated DC0-5Vvoltage value. The list of commonly used values is as follows:

DC0-5Vvoltage(V)	temperatureValue (℃)	Calculation Process
0	-30	(80-(-30))*(0-0)÷(5-0)+-30
1	-8	(80-(-30))*(1-0)÷(5-0)+-30
2	14	(80-(-30))*(2-0)÷(5-0)+-30
3	36	(80-(-30))*(3-0)÷(5-0)+-30
4	58	(80-(-30))*(4-0)÷(5-0)+-30
5	80	(80-(-30))*(5-0)÷(5-0)+-30

    As shown in the above formula, when measuring 2.5V, current DC0-5Vvoltage is 55℃。
  For example, the range is -30~80℃, the analog output is 0~10V DC0-10Vvoltage signal, temperature and DC0-10Vvoltage The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is temperature 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 temperature value, and C is the calculated DC0-10Vvoltage value. The list of commonly used values is as follows:

DC0-10Vvoltage(V)	temperatureValue (℃)	Calculation Process
0	-30	(80-(-30))*(0-0)÷(10-0)+-30
1	-19	(80-(-30))*(1-0)÷(10-0)+-30
2	-8	(80-(-30))*(2-0)÷(10-0)+-30
3	3	(80-(-30))*(3-0)÷(10-0)+-30
4	14	(80-(-30))*(4-0)÷(10-0)+-30
5	25	(80-(-30))*(5-0)÷(10-0)+-30
6	36	(80-(-30))*(6-0)÷(10-0)+-30
7	47	(80-(-30))*(7-0)÷(10-0)+-30
8	58	(80-(-30))*(8-0)÷(10-0)+-30
9	69	(80-(-30))*(9-0)÷(10-0)+-30
10	80	(80-(-30))*(10-0)÷(10-0)+-30

    As shown in the above formula, when measuring 5V, current DC0-10Vvoltage is 55℃。