Bio Instruments LATH-3T-485M
Phyto-Sensor leaf microclimate sensor for leaf and air temperature, humidity and VPD over RS485.
The Bio Instruments LATH-3T-485M is a Phyto-Sensor leaf microclimate sensor that measures leaf temperature, air temperature and humidity right at the leaf and derives VPD and absolute humidity, for crop monitoring in greenhouses. This Modbus RTU template reads all measured and derived values and the communication settings, and lets you change the address, baud rate and parity from ModbusCloud.
- Protocol
- Modbus RTU
- Connection
- RS485, 9600 baud
- Registers
- 25, read and write
- Brand
- Bio Instruments
- Key readings
- Leaf temperature · Air temperature · Leaf-air temperature difference · Relative humidity · Air VPD · Leaf VPD · Absolute humidity
- Available commands
- Modbus address · Baud rate · Parity
- Compatible models
- LATH-3T-485M
- Last updated
Registers (25)
25 read, 3 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Leaf Temperature | °C | Read | |||
| Air Temperature | °C | Read | |||
| Leaf-Air Temperature Difference | °C | Read | |||
| Air Relative Humidity | %RH | Read | |||
| Air VPD | kPa | Read | |||
| Leaf fVPD | kPa | Read | |||
| Air Partial Vapor Pressure | kPa | Read | |||
| Leaf Internal Vapor Pressure | kPa | Read | |||
| Air Saturated Vapor Pressure | kPa | Read | |||
| Air Absolute Humidity | g/m³ | Read | |||
| Air Absolute Humidity Mmol | Read | ||||
| Leaf Temperature Float | °C | Read | |||
| Air Temperature Float | °C | Read | |||
| Leaf-Air Temperature Difference Float | °C | Read | |||
| Air Relative Humidity Float | %RH | Read | |||
| Air VPD Float | kPa | Read | |||
| Leaf fVPD Float | kPa | Read | |||
| Air Partial Vapor Pressure Float | kPa | Read | |||
| Leaf Internal Vapor Pressure Float | kPa | Read | |||
| Air Saturated Vapor Pressure Float | kPa | Read | |||
| Air Absolute Humidity Float | g/m³ | Read | |||
| Air Absolute Humidity Mmol Float | Read | ||||
| Device Address | Read and write | ||||
| Baud Rate Code | Read and write | ||||
| Parity Code | Read and write |
Loading registers…
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Show leaf temperature, humidity and VPD at crop level on one dashboard for each greenhouse section.
- Get an email or webhook when air VPD goes above or below the limits you set, with one rule for each limit.
- Compare leaf VPD and the leaf-air temperature difference over 365 days of history to evaluate screens, lighting and misting.
- Use an automation that sends a webhook to your own system when VPD at the leaf crosses a threshold.
- Give each sensor its own address from ModbusCloud before you add more sensors to the same RS485 line.
Installation
Clip the leaf probe to the shaded underside of a healthy, fully expanded upper leaf so the air probe hangs below it, out of direct sun. Hang the signal conditioner upright with the cap on top.
Connect black to ground, yellow to RS485 B and white to RS485 A of the ModbusCloud Gateway, and red to a 5 to 24 Vdc supply. Terminate both ends of the bus with 120 Ω.
Give every sensor on the bus its own address with the Bio Instruments address tool or by writing Device Address. All sensors leave the factory with address 247.
In ModbusCloud, add a Modbus device with protocol RTU, the sensor address, 9600 baud and 8E1, and import this template.
Check that Leaf Temperature, Air Temperature and Air Relative Humidity show plausible values for the greenhouse.
Things to watch for
The sensor does not answer. What should I check?
Check 9600 baud, even parity, 1 stop bit and address 247 in ModbusCloud; many tools default to no parity. Swap A and B if nothing comes back, connect the black ground wire to the bus ground, and terminate both ends of the bus, because the sensor has no termination resistor inside.
Which absolute humidity should I use, g/m³ or mmol/m³?
Both registers hold the same absolute humidity of the air, once in grams per cubic metre and once in millimoles per cubic metre. The mmol register shows no unit in the portal. Use the one that matches your climate strategy; relative humidity and VPD have their own registers.
Why do I see every measured value twice?
The sensor gives each measurement as a scaled whole number and as a floating-point value. Both carry the same reading. Keep the one you want on your dashboards and remove the other from the Modbus device in ModbusCloud if you do not need it.
Can I change the address, baud rate or parity from ModbusCloud?
Yes, these three registers are writable. Writing is off per gateway by default; request it for the gateway in the portal. After a new address the sensor only answers on that address. Change baud rate or parity only when every device on the bus gets the same setting, and update the Modbus device in ModbusCloud right away.
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