Every Group Object is in fact a data point, i.e. it represents data.
In order to have a standardized interpretation of the data represented by each Group Object, data point types have been introduced.
E.g. suppose that a telegram is sent to a binary actuator in order to switch on a light somewhere in the building. Taking a closer look at this sentence two aspects can be distinguished:
- 'somewhere in the building'
- 'switch on'
The 'somewhere in the building' part is represented by the destination address of the telegram, i.e. the Group Address.
The 'switch on' part is at this moment unclear: it is not really certain how 'on' is encoded, i.e. without further knowledge only assumptions can be made and this is the reason why Datapoint Types are required.
Group Object 'configuration'
As such a Datapoint Type is a defined as being part of the Group Object configuration.
HOWEVER, the actual Datapoint Type information:
- is not stored in device memory
- is never included in a telegram
- is only stored in the ETS project
Datapoint Types are especially important for diagnostics, i.e. to enable ETS monitor interpreting data associated with Group Objects, e.g. instead of 'data = 85 A8', 'data = -6 °C' is shown.
Structure & notation
- data type: format + encoding
- size: value range + unit
- X: defines format + encoding
- YYY: defines value range + unit
The most often used Datapoint Types are:
- 1.yyy = boolean, like switching, move up/down, step
- 2.yyy = 2 x boolean, e.g. switching + priority control
- 3.yyy = boolean + 3-bit unsigned value, e.g. dimming up/down
- 4.yyy = character (8-bit)
- 5.yyy = 8-bit unsigned value, like dim value (0..100%), blinds position (0..100%)
- 6.yyy = 8-bit 2's complement, e.g. %
- 7.yyy = 2 x 8-bit unsigned value, i.e. pulse counter
- 8.yyy = 2 x 8-bit 2's complement, e.g. %
- 9.yyy = 16-bit float, e.g. temperature
- 10.yyy = time
- 11.yyy = date
- 12.yyy = 4 x 8-bit unsigned value, i.e. pulse counter
- 13.yyy = 4 x 8-bit 2's complement, i.e. pulse counter
- 14.yyy = 32-bit float, e.g. temperature
- 15.yyy = access control
- 16.yyy = string -> 14 characters (14 x 8-bit)
- 17.yyy = scene number
- 18.yyy = scene control
- 19.yyy = time + data
- 20.yyy = 8-bit enumeration, e.g. HVAC mode ('auto', 'comfort', 'standby', 'economy', 'protection')