Product

Technical Parameters

Technical parameter	Parameter value
Brand	TRANBALL
Noise range	30~130dB
Noise accuracy	±3%
Interface	RS485/TTL/DC0-3V
Power	DC5V 1A
Running temperature	-30~85℃
Working humidity	5%RH~90%RH

Product Selection

    Product DesignRS485,TTL,DC0-3VMultiple output methods, the products are divided into the following models depending on the output method.

Product model	output method
QM7903B	RS485总线
QM7903TTL	TTL

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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	noise	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 30~130dB, the analog output is 0~3V DC0-3Vvoltage signal, noise and DC0-3Vvoltage The calculation relationship is as shown in the formula: C = (A2-A1) * (X-B1) / (B2-B1) + A1, where A2 is noise range upper limit, A1 is the lower limit of the range, B2 is DC0-3Vvoltage output range upper limit, B1 is the lower limit, X is the currently read noise value, and C is the calculated DC0-3Vvoltage value. The list of commonly used values is as follows:

DC0-3Vvoltage(V)	noiseValue (dB)	Calculation Process
0	30.0	(130-30)*(0-0)÷(3-0)+30
1	63.3	(130-30)*(1-0)÷(3-0)+30
2	96.7	(130-30)*(2-0)÷(3-0)+30
3	130.0	(130-30)*(3-0)÷(3-0)+30

    As shown in the above formula, when measuring 1.5V, current DC0-3Vvoltage is 50dB。