The Modbus registers are listed in the RTD-NET datasheet (see attachment). Please also have a look at the article Using Modbus with our interfaces.
The register base is '0'.
- Please take note of the listed Modbus function codes to read and write to Holding and Input registers.
- Note that Holding Registers are read/write registers that are used for control parameters. These are used to control, but also monitoring (e.g. fan speed, mode etc.)
Note that the RTD-10 uses the same Modbus registers as the RTD-NET.
Data types
The RTD-Net supports two types of register, analogue Holding Registers and analogue Input Registers. Register Addresses are ‘0’ based in the range 0..65535. All analogue and digital values are accessed through these registers. All register values are 2 byte (16 bit) values.
Digital values are those where the values can only be either '0' or '1'. Analogue values on the other hand can retain any value in a specific range (e.g. setpoint temperature).
Please see the RTD-NET installation instructions for further details.
Additional Modbus registers:
- Holding Register 30000: 'Soft reset' - restarts the RTD interface
Note: Individual Heating and Cooling Setpoints
Some wired remote controllers display individual cooling and heating setpoints. It is not possible to read these setpoints individually. Reading of setpoint in Holding register 0001 is correct and this field shows setpoint in accordance to current mode.