Using Modbus indoor units parameters (e.g. Setpoint, ON/OFF) can be controlled and monitored, and parameters (e.g. Fault codes, Return Air Temperature) can be monitored.
The FDP3-BMS uses the same Modbus registers as the FDP3-Modbus interface.
- If you are using a FDP3 interface with AHU (Air Handling Unit) modification then refer to the articles FDP3-Modbus for AHU (Air Handling Units) or FDP3-BMS for AHU (Air Handling Units).
The Modbus registers are listed in the FDP3-Modbus datasheet (see attachment). Only these parameters lised in the installation instructions can be controlled or monitored. Note that the registers can be read and controlled regardless of the On/Off state of the indoor unit.
Please also have a look at the articles
- Using Modbus with our interfaces
- if you have more than one indoor unit wired to one FDP3 interface: FDP3: How to read data of a unit which is in a group.
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.)
Data types
The FDP3-Modbus supports two types of registers, 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 FDP3-Modbus installation instructions for further details.