Belimo Air-Water Actuator Modbus RTU
Controls communicative damper and valve actuators via Modbus RTU.
Modbus RTU template for Belimo communicative damper and valve actuators. Reads position feedback, sensor values, and actuator status. Allows setpoint control, override commands, and configuration of position limits and bus fail behavior.
- Protocol
- Modbus RTU
- Connection
- RS485, 38400 baud
- Registers
- 20, read and write
- Brand
- Belimo
- Key readings
- Relative Position (%) · Absolute Position (°) · Sensor 1 Value · Setpoint Analog (%) · Actuator Type · Malfunction and Service Information
- Available commands
- Setpoint (%) · Override Control · Min/Max Position (%) · Bus Fail Position
- Compatible models
- ..M(C)24A-MOD · ..R24A-MOD · ..V(K)24A-MOD · ..F24A-MOD · ..RF24A-MOD
- Last updated
Registers (20)
10 read, 10 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Actuator Type | Read | ||||
| Relative Position | % | Read | |||
| Absolute Position | °C | Read | |||
| Sensor 1 Value | Read | ||||
| Setpoint Analog | % | Read | |||
| Series Number 1st Part | Read | ||||
| Series Number 2nd Part | Read | ||||
| Series Number 4th Part | Read | ||||
| Firmware Version | Read | ||||
| Malfunction and Service Information | Read | ||||
| Setpoint | % | Write | |||
| Override Control | Write | ||||
| Command | Write | ||||
| Bus Termination | Write | ||||
| Minimum Position in Percent | % | Write | |||
| Maximum Position in Percent | % | Write | |||
| Sensor 1 Type | Write | ||||
| Bus Fail Position | Write | ||||
| Timeout for Bus Watchdog in s | s | Write | |||
| Setpoint Source | 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 actuator position and sensor values on a live cloud dashboard for remote HVAC oversight.
- Create an alert when the actuator reports a malfunction or service flag to speed up maintenance response.
- Adjust damper or valve setpoints remotely without an on-site visit, reducing travel time and cost.
- Log actuator position data over time to verify correct modulating behavior and diagnose control issues.
- Configure bus fail position and watchdog timeout remotely to ensure safe actuator behavior on communication loss.
- Track multiple Belimo actuators across sites in a single ModbusCloud project for centralized building management.
Installation
Wire the Modbus RTU bus (A and B terminals) from your ModbusCloud Gateway to the Belimo actuator, observing correct polarity.
Set the actuator Modbus address to a unique value on the bus and configure the baud rate to 38400 to match the template.
Enable bus termination on the last device by writing to register 99, or use a physical termination resistor at the end of the bus.
Configure the setpoint source register (address 118) so the actuator accepts setpoint commands from the Modbus bus.
Import the Belimo Air-Water Actuator Modbus RTU template in the ModbusCloud portal and assign it to the correct gateway and slave address.
Optionally configure the bus watchdog timeout (address 109) and bus fail position (address 108) for safe behavior on communication loss.
Things to watch for
The actuator does not respond on the Modbus bus. What should I check?
Verify that the baud rate on the actuator matches 38400 as required by this template. Also confirm the Modbus slave address is unique and that A/B wiring polarity is correct.
Setpoint commands are sent but the actuator does not move. Why?
The setpoint source register (address 118) must be configured to select the Modbus bus as the active setpoint input. If it is set to another source, the actuator ignores Modbus setpoint writes.
Do I need a physical termination resistor on the bus?
Belimo actuators support software-based bus termination via register 99. Write the appropriate value to enable termination on the last device. A physical resistor is not required if software termination is active.
What happens if the gateway loses communication with the actuator?
The actuator moves to the position defined in the bus fail position register (address 108) after the watchdog timeout (address 109) expires. Configure both registers to ensure safe damper or valve behavior during communication loss.
Want to see how it works?
