Data Sheet for Product

11
Siemens
A6V12071353_en--_b
Smart Infrastructure
2021-12-15
● 1-to-n Modbus/VRF gateway with Modbus master function or an additional Modbus mas-
ter unit
The Modbus master manages communication between VRF HMI units (slave function) and
the Modbus gateway to ensure proper operation. When using a Modbus gateway without
Modbus master function, an additional Modbus master unit is required.
RDF280 does not have termination resistor.
For VRF systems with multiple indoor units
If its VRF outdoor unit (2-pipe system) can only support either heating or cooling control se-
quence each time, only Modbus master or VRF HMI units selected as Master unit can select
the fixed heating or cooling control sequence for the VRF system.
● When heating mode is selected, the Modbus master also sets P01 of each connected
VRF HMI slave unit = 4 (HEAT/FAN) only.
● When cooling mode is selected, the Modbus master also sets P01 of each connected
VRF HMI slave unit = 5 (COOL/FAN/Dehumidification) or 6 (COOL/FAN) depending on
VRF operating modes supported by the indoor units.
If, e.g., heating is selected, RDF280 can only select VRF operating modes: HEAT or FAN. If
cooling is selected, RDF280 can only select VRF operating mode: COOL, FAN or Dehumidi-
fication
If a VRF outdoor unit (4-pipe system) allows both heating and cooling control sequences se-
lected by individual indoor units, each connected VRF HMI unit can be preset with P01 = 0,
1, 2 or 3 according to the VRF operating modes supported by the indoor and outdoor units.
Note that some indoor units do not support AUTO or Dehumidification.
Disposal
The device is considered an electronic device for disposal in accordance
with the European Guidelines and may not be disposed of as domestic
garbage.
● Dispose of the device through channels provided for this purpose.
● Comply with all local and currently applicable laws and regulations.
Note