Regmet RK-HTM-D..TFT touch screen controler
Measures and controls relative humidity and temperature via TFT touch screen controller
The Regmet RK-HTM-D is a TFT touch screen controller for measuring and setting relative humidity and temperature in interior spaces. This Modbus RTU template reads temperature and humidity values, and allows writing setpoints, operating modes, LCD settings, and display symbols via RS485.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 21, read and write
- Brand
- Regmet
- Key readings
- Temperature · Relative humidity
- Available commands
- Setpoint temperature · Setpoint humidity · Required mode 1 to 4 · LCD backlight and colors
- Compatible models
- RK-HTM-D
- Last updated
Registers (21)
2 read, 19 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| 1: 0x02 Relative humidity | % | Read | |||
| 0: 0x01 Temperature | °C | Read | |||
| 9: 0x10 Setpoint humidity | % | Write | |||
| 8: 0x09 Setpoint temperature | °C | Write | |||
| 16: 0x17 Required mode 1 | Write | ||||
| 17: 0x18 Required mode 2 | Write | ||||
| 76: 0x77 Offset temperature | °C | Write | |||
| 28: 0x29 Status register | Write | ||||
| 34: 0x35 LCD backlight day | Write | ||||
| 18: 0x19 Required mode 3 | Write | ||||
| 24: 0x25 Symbol at position 1 | Write | ||||
| 25: 0x26 Symbol at position 2 | Write | ||||
| 26: 0x27 Symbol at position 3 | Write | ||||
| 37: 0x38 LCD symbol color | Write | ||||
| 36: 0x37 LCD value color | Write | ||||
| 39: 0x40 Bit Field (external values) | Write | ||||
| 35: 0x36 LCD backlight time | Write | ||||
| 19: 0x20 Required mode 4 | Write | ||||
| 27: 0x28 Symbol at position 4 | Write | ||||
| 38: 0x39 LCD Backlight night | Write | ||||
| 77: 0x78 Offset relative humidity | % | Write |
Loading registers…
Send your device list
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
- Monitor room temperature and relative humidity across multiple zones on a centralized cloud dashboard.
- Adjust temperature and humidity setpoints remotely without physically visiting each room controller.
- Create alerts when indoor humidity exceeds a defined threshold for more than a set period.
- Switch operating modes centrally for seasonal changeovers or occupancy schedule updates.
- Log historical temperature and humidity data for compliance reporting in climate-sensitive environments.
- Display status symbols on the RK-HTM-D screen from the cloud to inform occupants about system events.
Installation
Wire the Regmet RK-HTM-D to the ModbusCloud gateway RS485 terminals (A to A, B to B) using twisted-pair shielded cable.
Set a unique Modbus slave address on the RK-HTM-D using its on-device menu or configuration tool.
Configure the ModbusCloud gateway serial port to 19200 baud, 8 data bits, odd parity, and 1 stop bit to match the RK-HTM-D defaults.
Import the Regmet RK-HTM-D template from the ModbusCloud template library and assign it to the correct gateway port and slave address.
Verify communication by checking that live temperature and humidity readings appear on the ModbusCloud dashboard.
If multiple RK-HTM-D units share the same RS485 bus, ensure each has a distinct address and add proper bus termination at the last device.
Things to watch for
The gateway cannot communicate with the RK-HTM-D. What should I check first?
Verify that the baud rate is set to 19200 and parity is set to odd (1 stop bit) on both the gateway and the controller. Also confirm that the A and B RS485 wires are not swapped.
Can I connect multiple RK-HTM-D controllers on one RS485 bus?
Yes. Each controller must have a unique Modbus slave address. Use a daisy-chain topology and place a 120 ohm termination resistor at the last device on the bus.
How do I select operating modes via Modbus?
The template includes write registers for modes 1 through 4. Each register accepts a value from 1 to 68, corresponding to the predefined mode library of the RK-HTM-D. Set the register to the desired mode number.
Can I change the LCD backlight and colors remotely?
Yes. The template exposes writable registers for LCD backlight intensity and color settings. Changes take effect immediately on the TFT display.
Want to see how it works?
