The sensor does not respond on the Modbus bus. What should I check?

Verify that the RS485 wiring is correct (A to A, B to B, GND to GND) and that the baud rate on both the sensor and the gateway is set to 38400. Also confirm there is no slave address conflict with other devices on the same bus.

CO2 readings seem inaccurate or drifting. Can I correct this remotely?

Yes. The template includes a write register for CO2 offset starting at address 100. You can apply a correction value through ModbusCloud without visiting the site. The dual-channel CO2 technology should minimize long-term drift.

How do I change the measurement units from Celsius to Fahrenheit?

Use the unit system selection register at address 400. Writing the appropriate value will switch temperature and related readings to the desired unit system.

Can I configure the 0 to 10 V analog output range via Modbus?

Yes. Registers 508 and 509 allow you to set the minimum and maximum output voltage. Output range limits can also be adjusted through registers starting at address 200.

Free Modbus template: Belimo Temperature Humidity CO2 Sensor Modbus RTU

Name: Belimo Temperature Humidity CO2 Sensor Modbus RTU
Brand: Belimo
SKU: 5e6834e8-63a4-4b7c-a49c-c2c81867ea2e

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Free Modbus template: Belimo Temperature Humidity CO2 Sensor Modbus RTU | ModbusCloud

Registers (39)

14 read / 25 write

Name	Address	Function	Type	Unit	Access
Temperature	0	FC03	int16	°C	R
Relative Humidity	1	FC03	int16	%RH	R
Absolute Humidity	2	FC03	int16	g/m3	R
Enthalpy	3	FC03	int16	kJ/kg	R
Dew Point	4	FC03	int16	°C	R
CO2	5	FC03	int16	ppm	R
Sensor Detection	501	FC03	uint16		R
Hardware version main circuit board	502	FC03	uint16		R
Firmware version main circuit board	503	FC03	uint16		R
Hardware version RS 485 module	504	FC03	uint16		R
Firmware version RS 485 module	505	FC03	uint16		R
Maximum output voltage	509	FC03	uint16	V	R
Operating hours counter	510	FC03	uint16	h	R
Device Detection	500	FC03	uint16		R
Offset Temperature	100	FC06	int16	°C	W
Offset Relative Humidity	101	FC06	int16	%RH	W
Offset CO2	102	FC06	int16	ppm	W
Lower Limit Temperature	200	FC06	int16	°C	W
Upper Limit Temperature	201	FC06	int16	°C	W
Lower Limit Relative Humidity	202	FC06	int16	%RH	W
Upper Limit Relative Humidity	203	FC06	int16	%RH	W
Lower Limit Absolute Humidity	204	FC06	int16	g/m3	W
Upper Limit Absolute Humidity	205	FC06	int16	g/m3	W
Lower Limit Enthalpy	206	FC06	int16	kJ/kg	W
Upper Limit Enthalpy	207	FC06	int16	kJ/kg	W
Lower Limit Dew Point	208	FC06	int16	°C	W
Upper Limit Dew Point	209	FC06	int16	°C	W
Lower Limit CO2	210	FC06	int16	ppm	W
Upper Limit CO2	211	FC06	int16	ppm	W
Channel Temperature	300	FC06	uint16	°C	W
Channel Relative Humidity	301	FC06	uint16	%	W
Channel Absolute Humidity	302	FC06	uint16		W
Channel Enthalpy	303	FC06	uint16		W
Channel Dew Point	304	FC06	uint16	°C	W
Channel CO2	305	FC06	uint16	ppm	W
Selection of the Unitary System	400	FC06	uint16		W
Minimum output voltage	508	FC06	uint16	V	W
Countdown for maintenance	511	FC06	uint16	h	W
Countdown for visual inspection	512	FC06	uint16	h	W