Why do I see unexpected values when reading address 1 or address 5?

Some registers share the same address but differ by function code or context. Address 1 maps to both Mode and Breezer status, and address 5 maps to both Target temperature and Beeper. The template handles this distinction, but manual polling with the wrong function code will return incorrect data.

What baud rate should I use for the ONOKOM TN-1-MB-B?

The default baud rate is 9600. Make sure your ModbusCloud gateway serial port is also configured to 9600 baud, 8 data bits, no parity, and 1 stop bit unless the ONOKOM documentation specifies otherwise.

Can I accidentally lock myself out by writing to the wrong register?

Yes. The baud rate and Modbus slave address registers are writable. If you change them unintentionally, you will lose communication until you reconfigure either the gateway or your bus settings to match. Double check register addresses before issuing write commands.

Is RS-485 termination required?

If the ONOKOM gateway is at the end of the RS-485 bus, enable a 120 ohm termination resistor on that segment. Unterminated buses can cause CRC errors and intermittent read failures, especially on longer cable runs.

Free Modbus template: ONOKOM AIR TN-1-MB-B

Name: ONOKOM AIR TN-1-MB-B
Brand: Onokom
SKU: 8c73691f-fbb8-4e67-8489-3c273b52020a

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Free Modbus template: ONOKOM AIR TN-1-MB-B | ModbusCloud

Registers (19)

16 read / 12 write

Name	Address	Function	Type	Unit	Access
Breezer status	1	FC01	uint16		R/W
Screen light	2	FC01	uint16		R/W
Air heating	11	FC01	uint16		R/W
Outdoor air supply	15	FC01	uint16		R/W
Breezer is on the line	20	FC01	uint16		R
Mode	1	FC03	uint16		R/W
Air temperature at the breezer outlet	3	FC03	uint16	°C	R
Breezer inlet air temperature	4	FC03	uint16	°C	R
Fan speed	7	FC03	uint16		R/W
Control board temperature	23	FC03	uint16	°C	R
Power board temperature	24	FC03	uint16	°C	R
Days to filter replace	644	FC03	uint16	count	R
Set days to next filter replace	634	FC03	uint16	count	R/W
Filter needs to be replaced	33	FC02	uint16		R
Target temperature	5	FC03	uint16	°C	R/W
Beeper	5	FC02	uint16		R/W
Reset filter counter	14	FC05	uint16		W
Baud rate	110	FC06	uint16		W
Modbus address	128	FC06	uint16		W

ONOKOM AIR TN-1-MB-B

Overview

Key readings

Available commands

Use cases

Installation

Things to watch for

Registers (19)

Working with Modbus in your projects?

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