Technical Manual
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Operating mode switching via 1 byte is done via a single object, the DPT 20.102 HVAC Mode
according to KNX specification. In addition, 2 objects are available for visualisation, firstly the 1 byte
object "DPT_HVAC Status" and secondly the 2 byte object "DPT_RHCC Status". For operating mode
selection, a hex value is sent to the "mode selection" object. The object evaluates the received hex
value and thus switches on the corresponding operating mode and switches off the previously active
operating mode. If all operating modes are switched off (Hex-value = 0), the operating mode Standby
will be switched on.
The hex values for the individual operating modes can be taken from the following table:
Mode selection (HVAC Mode)
Hex-Value
Comfort
0x01
Standby
0x02
Night
0x03
Frost/Heat protection
0x04
Table 40: Hex values of HVAC Modes
The following example illustrates how the controller processes received hex values and thus switches
operating modes on or off. The table is based on each other from top to bottom.
Example (set priority: Frost/Comfort/Night/Standby):
Received Hex value
Processing
Set operating mode
0x01
Comfort = 1
Comfort
0x03
Comfort = 0
Night = 1
Night
0x02
Night = 0
Standby = 1
Standby
0x04
Standby = 0
Frost/Heat protection = 1
Frost/Heat protection
Table 41: Example - Mode selection via 1 Byte
The DPT HVAC Status communication object, DPT_HVAC Status (without number) according to KNX
specification, sends the corresponding hex value for the currently set operating mode. If several
statements apply, the hex values are added together and the status symbol then outputs the added
hex value. The hex values can then be read out by a visualisation system.
The following table shows the hex values associated with the individual messages:
Bit
DPT HVAC Status
Hex-Value
0
Comfort
1 = Comfort
0x01
1
Standby
1 = Standby
0x02
2
Night
1 = Nacht
0x04
3
Frost/Heat protection
1 = Frost/Heat protection
0x08
4
5
Heating/Cooling
0 = Cooling/ 1 = Heating
0x20
6
7
Frostalarm
1 = Frostalarm
0x80
Table 42: Hex values - HVAC Status
For example, if heating is carried out in comfort mode, the communication object outputs the value
20 (for heating) + 1 (for comfort mode) = 21.