The product uses industrial-grade chips and high-precision imported SHT20 temperature and humidity sensors to ensure the excellent reliability, high precision and interchangeability of the product. Using RS485 hardware interface (with lightning protection design), the protocol layer is compatible with the standard industrial Modbus-Rtu protocol. This product integrates the MODBUS protocol and the common protocol. The user can choose the communication protocol by himself. The common protocol has an automatic upload function (connecting RS485 and passing the serial port adjustment tool will automatically output temperature and humidity).
Features:
Industrial grade product, high progress SHT20 temperature and humidity sensor, RS485 communication;
Standard MODBUS protocol and common protocol are integrated, users can choose communication protocol by themselves;
The baud rate can be set by yourself;
The common protocol has an automatic upload function, and the upload rate can be set by yourself.
Product parameters:
Working voltage: DC4-30V (the highest should not exceed 33V)
Maximum power: 0.2W
Working temperature: temperature -20℃+60℃, humidity 0%RH-100%RH
Control accuracy: temperature ±0.3℃(25℃), humidity ±3%RH(25℃)
Output interface: RS485 communication (standard MODBUS protocol and custom common protocol), see protocol description for details
Device address: 1-247 can be set, the default is 1
Baud rate: default 9600 (users can set by themselves), 8 data, 1 stop, no parity.
products used in the function code:
0 x03:read holding registers
0 x04:read input registers
0 x06:write a single holding register
0 x10:write multiple hold registers
Modbuscommunication Format:
the host sends a data frame:
|
the slave address |
function Code |
register Address the high byte |
register Address the low byte |
number of registers the high byte |
number of registers the low byte |
CRC the high byte |
CRC the low byte |
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slave response data frame:
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the slave address |
in response to the function code |
the number of bytes |
register1data the high byte |
register1data the low byte |
registerNdata the high byte |
registerNdata the low byte |
CRC the high byte |
CRC the low byte |
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MODBUSthe command frame
host reads temperature command frames(0 x04):
|
the slave address |
function Code |
register Address the high byte |
register Address the low byte |
number of registers the high byte |
number of registers the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x04 |
0x00 |
0x01 |
0x00 |
0x01 |
0x60 |
0x0a |
slave response data frame:
|
the slave address |
function Code |
the number of bytes |
temperature the high byte |
temperature the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x04 |
0x02 |
0x01 |
0x31 |
0x79 |
0x74 |
the temperature value= 0 x131,to decimal conversion305actual temperature value= 305 / 10=30.5℃
note: temperature is marked16decimal number, temperature value= 0 xFF33,to decimal conversion-205the actual temperature= -20.5℃;
host reads humidity command frames(0 x04):
|
the slave address |
function Code |
register Address the high byte |
register Address the low byte |
number of registers the high byte |
number of registers the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x04 |
0x00 |
0x02 |
0x00 |
0x01 |
0xC1 |
0xCA |
slave response data frame:
|
the slave address |
function Code |
the number of bytes |
humidity the high byte |
humidity the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x04 |
0x02 |
0x02 |
0x22 |
0xD1 |
0xBA |
humidity value= 0 x222,to decimal conversion546actual humidity value= 546 / 10 = 54.6%;
continuously read temperature and humidity command frames(0 x04):
|
the slave address |
function Code |
register Address the high byte |
register Address the low byte |
number of registers the high byte |
number of registers the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x04 |
0x00 |
0x01 |
0x00 |
0x02 |
0x20 |
0x0B |
slave response data frame:
|
the slave address |
function Code |
the number of bytes |
temperature the high byte |
temperature the low byte |
humidity the high byte |
humidity the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x04 |
0x04 |
0x01 |
0x31 |
0x02 |
0x22 |
0x2A |
0xCE |
read the content of the maintenance register(0 x03):
take reading the slave address as an example:
|
the slave address |
function Code |
register Address the high byte |
register Address the low byte |
number of registers the high byte |
number of registers the low byte |
CRC the high byte |
CRC the low byte |
|
0x01 |
0x03 |
0x01 |
0x01 |
0x00 |
0x01 |
0xD4 |
0x0F |
PARAMinstructions:
TC:0.0,HC:0.0,BR:9600,HZ:1->temperature correction0.0humidity correction value0.0the baud rate9600report rate1Hz
SLAVE_ADD:1->MODBUSthe slave address0x01
On Dec 7, 2023 at 21:55:27 PST, seller added the following information: