When several indoor units are wired to the same RTD interface on one P1P2 wired remote controller network they are treated as a group. This means any command sent to the RTD interface applies to all these units. However, data (like Fault code, RA temperature, Thermo On etc) can be read individually from each indoor unit via Modbus. For lists of available readback data please refer to the installation instructions of the RTD interface in use.
*Note that some data is only available when the Remote Controller is configured to a specific mode. For example to read with the RTD-NET the Coil In/Out temperatures the remote controller needs to be configured to MAIN P1P2 mode. Other data (like Remote Controller temperature sensor value when the RTD-NET is used) may not be available at all if a group is controlled. Refer to the installation instructions of the RTD in use for details.
General (Group) vs Individual (Unit) Readback data
The RTD interface to which a group of indoor units is wired allows reading group and (individual) unit data. General data can be any value in any (Modbus) Holding register, or in specific Input Registers.
If for example a Holding register's value is changed through a hardwired input (S1 - S6..note that not all RTD interfaces have hardwired inputs) then this value is applicable for all units and can be read using the Modbus command for reading Holding Registers.
The difference between (Modbus) group Input Registers and (individual) unit Input Registers is:
The group registers hold information which may be the average value of the units, data, or status of at least one of the units while the unit registers hold information of a specific unit within the group.
*Note: Input Registers do not effect operation of the indoor units.
Example:
RTD-NET: Read the Return Air temperature of a group of 16 units (the 'I' before the register address inidicates that this is an Input Register):
* I0023 gives average of all units' return air temperatures
* I0123 gives return air temperature of unit 1
* I0223 gives return air temperature of unit 2
...
* I1623 gives return air temperature of unit 16
The value of a Readback Input Registers for which no indoor unit exists is '0'.
As shown above the Input Register address of unit readback registers is 'xx23' ('xx' > 0). The 'xx' is the P1P2 network address of this specifc indoor unit. This P1P2 address cannot be set with the RTD interface. For further information on setting this address please refer to the indoor unit's installation instructions, the remote controller's manuals, or contact Daikin Technical Support.