Bio Instruments LAT-2T-485M
Phyto-Sensor dual probe for leaf temperature, air temperature and their difference over RS485.
The Bio Instruments LAT-2T-485M is a Phyto-Sensor dual probe that measures leaf temperature, nearby air temperature and the difference between them at the same spot on the plant, for crop monitoring in greenhouses. This Modbus RTU template reads all three 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
- 9, read and write
- Brand
- Bio Instruments
- Key readings
- Leaf temperature · Air temperature · Leaf-air temperature difference · Modbus address · Baud rate · Parity
- Available commands
- Modbus address · Baud rate · Parity
- Compatible models
- LAT-2T-485M
- Last updated
Registers (9)
9 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 | |||
| Leaf Temperature Float | °C | Read | |||
| Air Temperature Float | °C | Read | |||
| Leaf-Air Temperature Difference Float | °C | Read | |||
| Device Address | Read and write | ||||
| Baud Rate Code | Read and write | ||||
| Parity Code | Read and write |
Loading registers…
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Use cases
- Show leaf temperature, air temperature and their difference side by side on a greenhouse dashboard.
- Get an email or webhook when the leaf-air temperature difference rises above a threshold you set.
- Keep 365 days of history to compare the leaf-air difference between days, screens and lighting strategies.
- Let automatic monitoring flag a probe value that stays exactly the same for hours.
- 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. Keep both out of direct sun and strong air movement, and tape the cable near the leaf base.
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 and Air Temperature show plausible values close to each other.
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.
Why is the leaf-air temperature difference sometimes below zero?
The difference is a signed value, so it goes below zero or above zero depending on whether the leaf is cooler or warmer than the air around it. Both cases are normal. Shield the probes from direct sun, because sunlight on a probe distorts the difference.
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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