Modbus Registers
The Sensorbee Modbus Lite exposes two register groups over Modbus RTU:
- ·Holding registers — read/write configuration parameters: slave address, baud rate, parity, stop bits.
- ·Input registers — read-only sensor measurements (the live values from the connected sensors).
For most deployments, configuration is done over USB-C with the configuration menu. But if you need to, you can configure the unit entirely over Modbus by writing to the holding registers.
Configuration registers
These parameters are read/write. Once written, the value is stored in non-volatile memory and persists across reboots — the new value becomes the unit's default configuration.
Register data is represented as a 16-bit unsigned integer.
| Parameter | Address | Address (hex) | Allowed values | Default | Firmware |
|---|---|---|---|---|---|
| Slave address | 0 | 0x0000 | 1 to 247 | 1 | ≥ 1.0.0 |
| Baud rate | 8 | 0x0008 | 9600 / 115200 / 192000 / 576000 | 9600 | ≥ 1.0.0 |
| Parity | 38 | 0x0026 | 0 = None / 1 = Odd / 2 = Even | 0 (None) | ≥ 2.0.0 |
| Stop bits | 39 | 0x0027 | 1 = 1 stop bit / 2 = 2 stop bits | 2 | ≥ 2.0.0 |
Invalid values are rejected by the Modbus protocol even though the register field can hold any 32-bit value. Only write the allowed values listed above.
Measurement registers
Sensor measurement values are stored in the Modbus input registers. The full register map is on the next page — broken out by sensor type for navigation:
- ·Modbus Register Map — top-level reference.
For the underlying gas-sensor calculations (offset constant, sensitivity, temperature compensation), see Gas Sensor Calculations.