SPECIFICATIONS

1. Product Parameters

- Name: 3-in-1 Barometric Pressure, Temperature and Humidity Sensor
- Model: GL-ATH30
- Rated Voltage: 5 ~ 30V DC
- Power: Less than 0.1W
- Accuracy:
Barometric Pressure ±0.15kPa @25℃ 101kPa
Humidity ±3%RH（60%RH, 25℃）
Temperature ±0.5℃ (25℃）
- Range: 0 ~ 120kPa, -40℃ ~ 80℃, 0 ~ 100%RH
- Output Port RS485
- Communication Protocol: Modbus RTU
- Baud Rate: 9600bits per second
- Default Address: 0x01
- Resolution: Humidity 0.1%RH, Temperature 0.1℃, Barometric Pressure 0.01kPa
- Protection Level: Not water-proof (for indoor use only)

2. Attractive Features

2.1 Sensor Calibrated Before Exwork
The temperature and humidity data of sensor are precisely calibrated before leaving factory. No calibration needed anymore before use.

2.2 Modbus RTU Protocol
Under Modbus RTU protocol, the temperature and humidity sensor can be connected to PC, MCU (Micro Controller Unit) and PLC for data communication.
To connect to PC, an RS485 to USB convertor is needed and included in one of the SKUs.
To connect to MCU and PLC, an RS485 to TTL/232 convertor (not included) is needed.

2.3 Advanced Chip Embedded

The sensor is equipped with an advanced chip from Switzerland. It contributes to the precise and stable data measurement.

2.4 Visible Communication - LED Indicator
The PCB bears a red LED indicator.
When power on, the indicator is flashing slowly.

2.6 Energy-Saving and Wide Range of Power Supply
- The PCB of sensor is energy-saving. It consumes less than 0.1 Watt.
- Power Supply can be DC 5~28V. This wide range provide more flexibility for users.

3. Product Dimensions and Terminals Definition

Note: Dimensions measured by hands may have small deviations.

The sensor box can be installed in standard DIN track (not included) or fixed by 2 screws (M3 recommended).

Terminal Definnition:
① RS485 A
② RS485 B
③ + Positive of Power (VCC)
④ - Negative of Power (GND)
⑤ Idle (Not Used)

4. Communication Protocol - Modbus TRU

4.1 Basic Parameters
- Baud Rate: 9600 bps
- Data bit: 8
Stop bit: 1
- Parity check: None
- Verification: CRC-16/Modbus
- Read Code: 0x03 (0x indicates the data is hexadecimal)
- Write Code: 0x06

4.2 RS485 Modbus Protocol Format

RS485 Modbus Register Definition

Note: "0x" in the table indicates the address/code are hexademical.

4.3 Communication Examples

To read barometric pressure
Host Sends: 01 03 00 04 00 01 31 84 (0x31 84 is the 16-bit CRC verification code)
Sensor (GL-ATH30) Replies: 01 03 02 27 3B A7 84
2 bytes of pressure are 0x273B = 10043,
10043 divided by 10 is the value in hPa and by 100 is the value in kPa.
So the barometric pressure is 100.43kPa.


To read humidity and temperature:
Host Sends: 01 03 00 00 00 02 0B 94
Sensor Replies: 01 03 04 02 E0 01 1F 2C 07

2 bytes of humidity are 0x02E0 = 736.
736 divided by 10 comes the humidity value 73.6%RH.

2 bytes of temperature are 0x011F= 287.
287 divided by 10 comes the temperature value 28.7°C.

To read Baud Rate:
Host (TX): 01 03 07 D1 00 01
Client (RX): 01 03 02 00 02

To read client address:

Host (TX): 01 03 07 D0 00 01
Client (RX): 01 03 02 00 01

To change client/sensor address from 01 to 02:
Host (TX): 01 06 07 D0 00 02
Client (RX): 01 06 07 D0 00 02

If forgoten, the client address can be checked in this way. Use broadcast address OxFF as substitue and only 1 client is connected.

Host (TX): FF 03 07 D0 00 01
Client (RX): 02 03 02 00 02
The address is 0x02.

Refer to the screenshot of Serial Port Tester below.

Barometric pressure trend during typhoon weather