Modbus Temperature Sensor RS485 Temperature Humidity Transmitter with Modus RTU

1.Product Overview

XZ-MUS-LTH adopts MODBUS protocol, CRC check standard MODBUS-CRC16, factory default baud rate 9600bps, 8N1 data format.

Note: During parameter setting, if the address cannot be confirmed, only one terminal device is kept on the bus, and the address uses FF, and the parameters can be reset. The device with the FF address is an invalid device.

2. Product selection and parameters

3.Pin definitions

4.Communication Protocol

4.1 Parameter setting and read data protocol

XZ-MUS-LTH adopts MODBUS protocol, CRC check standard MODBUS-CRC16, factory default baud
rate 9600bps, 8N1 data format.

Note:During parameter setting, if the address cannot be confirmed, only one terminal
device is kept on the bus, and the address uses FF, and the parameters can be
reset. The device with the FF address is an invalid device.

4.1.1 Modify XZ-MUS-LTH address, modify the address range 0x01～0xFF.

FF 06 40 01 01 8B 43ID: 0xFF （Used when the sensor address cannot be confirmed），0x01～0xFEFN: 0x06RG: 0x4001 Address register address 2 bytesSETID：（0x01～0xFE）set the address of XZ-MUS-LTH

CRC： MODBUS-CRC16

Return： 01 06 01 01 04 E7

4.1.2.Modify the serial baud rate of the XZ-MUS-LTH, and modify the baud rate range from 1200bps to 19200bps.

01 06 40 02 08 0F 77ID: 0x01～0xFEFN: 0x06RG: 0x4002 Baud rate register address 2 bytesSETBU：（0x01～0x08）set the baud rate of XZ-MUS-LTH from 1200bps to 115200bps01:1200bps 02:2400bps 03:4800bps 04:9600bps05:19200bps CRC： MODBUS-CRC16

Return： 01 06 01 08 2D 76

4.1.3 Modify the serial port parity bit of XZ-MUS-LTH and change the parity bit to no parity, even parity, and odd parity.

01 06 40 03 02 74 E5ID: 0x01～0xFEFN: 0x06RG: 0x4003 Check bit register address 2 bytesSETVF：（0x01～0x03）set the check bit of XZ-MUS-LTH01: No parity 02: Even parity 03: Odd parityCRC： MODBUS-CRC16

Return： 01 06 01 02 67 D7

4.1.4 Modify the serial port stop bit of XZ-MUS-LTH, modify the stop bit to 1bit, 2bit.

01 06 40 04 01 80 4C

ID:0x01～0xFE

FN:0x06

RG:0x4004 Stop bit register address 2 bytes

SETST：（0x01～0x03）set stop bit of XZ-MUS-LTH

01:1bit  02:2bit

CRC：MODBUS-CRC16

Return： 01 06 01 01 04 E7

4.1.5 Read the data of XZ-MUS-LTH parameter register.

01 04 40 01 00 05 AF C5

ID:0x01～0xFE

FN:0x04

RG:0x4001 Start register address 2 bytes

LEN：0x0004 Read register
length, read 4 register values

CRC：MODBUS-CRC16

Return： 01 04 05 01 08 02 01 01 F6 A7

4.2.Sensor data reading protocol

ID: 0x01～0xFE sensor address

FN: 0x03

RG： 0x0001 temperature sensor address， 0x0002 humidity sensor address，

Return：01 03 06 01 07 02 FE FF A0 29 03

Register 1: Temperature, 16-bit signed number, the reading is divided by 10 to get the temperature value.

0x0107 = 26.3℃ 0xFF32 = -20.6℃

Register 2: Humidity, a 16-bit unsigned number, the reading is divided by 10 to get the relative humidity.

0x02FE = 76.6%