AMR-OP75RHRC/01 control unit, temperature, humidity, CO2, touch graphic display, RS485, RTD/NTC, relay
Monitors temperature, humidity, and CO2 with touch display and internal relay via RS485.
The AMIT AMR-OP75RHRC/01 is a wall-mounted control unit that measures temperature, humidity, CO2 concentration, and RTD/NTC resistance. This Modbus RTU template reads key environmental values and controls the internal relay, outdoor temperature display, info icon, and display title characters via RS485.
- Protocol
- Modbus RTU
- Connection
- RS485, 115200 baud
- Registers
- 30, read and write
- Brand
- AMIT
- Key readings
- Temperature · Relative humidity · CO2 concentration · RTD input resistance · Device status · Firmware version
- Available commands
- Relay output · Outdoor temperature display · Info icon · Display title characters
- Compatible models
- AMR-OP75RHRC/01
- Last updated
Registers (30)
16 read, 18 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Relativní vlhkost | % | Read | |||
| co2 | ppm | Read | |||
| teplota | °C | Read | |||
| ID modulu | Read | ||||
| Firmware | Read | ||||
| Guard Time | ms | Read | |||
| Baud Rate | Read | ||||
| Odpor RTD vstupu | ohm | Read | |||
| StatusSet | Read and write | ||||
| StatusReset | Read | ||||
| Status | Read | ||||
| FReq | Read | ||||
| Informační Lišta | Read and write | ||||
| RČas2 | s | Read and write | |||
| RČas3 | s | Read | |||
| Titulek | Read and write | ||||
| rele | Write | ||||
| Venkovní teplota200 | °C | Write | |||
| InfoIkona | Write | ||||
| Titulek02 | Write | ||||
| Titulek03 | Write | ||||
| Titulek04 | Write | ||||
| Titulek06 | Write | ||||
| Titulek05 | Write | ||||
| Titulek07 | Write | ||||
| Titulek09 | Write | ||||
| Titulek08 | Write | ||||
| Titulek10 | Write | ||||
| Titulek11 | Write | ||||
| Titulek12 | Write |
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Use cases
- Monitor indoor temperature, humidity, and CO2 levels on a live cloud dashboard for facility managers.
- Create an alert when CO2 concentration exceeds a threshold to trigger ventilation in classrooms or offices.
- Control the internal relay remotely to switch ventilation or signaling equipment from the cloud.
- Log RTD or NTC resistance values over time to detect sensor drift or calibration issues.
- Display outdoor temperature on the unit screen by writing the value from a remote weather source via the cloud.
- Track device status and firmware version across multiple installed units for maintenance planning.
Installation
Wire the AMIT AMR-OP75RHRC/01 RS485 A and B terminals to the corresponding RS485 port on your ModbusCloud Gateway, and connect the GND reference.
Configure the gateway serial port to 115200 baud, odd parity (1), and 8 data bits to match the device settings.
Set a unique Modbus RTU slave address on the AMR-OP75RHRC/01 and enter the same address in the ModbusCloud gateway configuration.
Import the AMIT AMR-OP75RHRC/01 template from the ModbusCloud template library and assign it to the correct gateway port and slave address.
The device expects a write to register 100 every 30 seconds to hide its broken communication icon. ModbusCloud writes registers at most once per minute, so the icon will stay visible, while reading values works normally.
Verify that temperature, humidity, and CO2 readings appear correctly on the ModbusCloud dashboard before completing the installation.
Things to watch for
Why does the device display show a broken communication icon?
The AMR-OP75RHRC/01 expects a write to register 100 every 30 seconds. If this heartbeat write is not configured, the unit displays a warning icon. Data communication still works normally without it, but the icon may confuse end users. ModbusCloud writes registers at most once per minute, so it cannot keep up this 30-second heartbeat and the icon will stay visible, while reading values works normally.
What baud rate and parity settings are required?
The device requires 115200 baud with odd parity (1) and 8 data bits. Both the Modbus gateway and the device must use identical serial settings, otherwise communication will fail.
How do I write custom text to the touch display?
Each character position on the display has its own dedicated Modbus register. The template only includes key registers. Consult the AMIT device manual for the full register map and create additional registers in ModbusCloud as needed.
What register format is used for sensor values?
Temperature, humidity, CO2, and RTD values use Float32 (two consecutive 16-bit registers). Ensure the byte order (word swap) in your gateway matches the format specified in the AMIT documentation.
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