Regmet CHM1CF - TFT display controller

Use cases

• Monitor room temperature, humidity, and CO2 concentration on a live cloud dashboard for each zone.
• Adjust temperature and humidity setpoints remotely without sending a technician to site.
• Create an alert when CO2 concentration exceeds a defined threshold for more than five minutes.
• Assign predefined status symbols to the three display positions remotely to indicate system states.
• Log indoor air quality trends over time and generate reports for building management or compliance.
• Calibrate temperature and humidity offsets remotely using the offset registers at addresses 76 and 77.

Installation

1. 1Wire the Regmet CHM1CF to the RS485 bus of your ModbusCloud gateway (MCG or MLP series), connecting A, B, and GND terminals.
2. 2Set the Modbus slave address on the CHM1CF according to the device documentation, ensuring it does not conflict with other devices on the bus.
3. 3Configure the gateway serial port to 19200 baud, 8 data bits, even parity (1), and 1 stop bit to match the CHM1CF default settings.
4. 4Import the Regmet CHM1CF template from the ModbusCloud template library and assign it to the correct gateway and slave address.
5. 5Verify communication by checking that live temperature, humidity, and CO2 values appear on the ModbusCloud dashboard.
6. 6If needed, adjust the calibration offset registers for temperature and humidity through the template to match a reference instrument.

Things to watch for

01

The gateway cannot communicate with the CHM1CF. What should I check?

Verify that the baud rate is set to 19200 and parity is set to even (1 stop bit) on both the gateway and the device. Also confirm that the A and B wires are not swapped and that the Modbus slave address matches the template configuration.

02

Temperature or humidity readings seem slightly off compared to a reference sensor.

Use the calibration offset registers at address 76 (temperature) and address 77 (relative humidity) to apply a correction. These can be written remotely through the ModbusCloud template.

03

Can I display external values on the CHM1CF screen via Modbus?

Yes. The bit field register at address 39 controls whether the display shows external values. Set the appropriate bits through the template to enable external value display, then write the desired values to the corresponding registers.

04

How do I assign a symbol to one of the three display positions?

Write the symbol number (1 to 163) to the corresponding symbol position register (position 1, 2, or 3) via the template. Each symbol can be displayed in a configurable color set through the symbol color register.

Registers (22)

6 read / 19 write

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