Instruction manual

NetLinx Programming

NXB-KNX KNX Communications Gateway

User Data (DPT) Specifications and Requirements

KNX defines the User data in different Telegrams as Data Point Types (or "DPT"s)

KNX defines DPT IDs numerically, in the form major.minor (for example: DPT 1.001 or DPT 1.002), where the major

ID is designated a data length in bits or bytes (8-bit octets), and the minor ID defines format and encoding.

The same data length may be reused in several DPT major IDs. For example, DPT 5s and DPT 6s are

1-Byte in data length, while DPT 7s, DPT 8s and DPT 9s are 2-Bytes in data length.

In essence, the NXB-KNX supports User Data (DPTs) simply in terms of data length, thereby supporting most DPTs.

The supported data lengths are:

6-bit data length DPTs are defined in KNX, but are not widely used. In practice, 1-Byte data lengths replace

6-bit definitions, and are typically used by KNX devices.

The KNX-defined 8-Byte data length is "date time", but KNX devices typically use 3-Byte DPT 10 "time"

and 3-Byte DPT 11 "date" for economy (relative to the lengthier 8-Byte combined format) and for more

flexible use.

The module application is responsible for interpreting User Data per each KNX device's definitions.

The NXB-KNX recognizes the most commonly used User Data formats, and translates User Data to simplify most

module application responsibilities.

The supported User Data format options are:

The NXB-KNX supports the following commonly used DPT (User Data) data lengths:

Bits Bytes

• 1-bit • 1-Byte (=8-bits/octet)

•2-bit •2-Byte

•4-bit •3-Byte

•4-Byte

• 14-Byte Text, HexText

•EIS5

•Date

•Time

Supported DPT Data Lengths

Data Length Description / Example

• 1-bit DPT 1s are Boolean (switch)

• 2-bit DPT 2s "1-bit controlled" (control)

• 4-bit (or

"Dim4")

DPT 3s "3-bit controlled" (used as on/off with dimmer step values)

• 1-Byte DPT 5s "8-bit unsigned" (also DPT 4s, DPT 6s, DPT 200s, DPT 201s)

• 2-Byte DPT 9s "2-octet float" (also DPT 7s, DPT 8s)

• 3-Byte DPT 10s "time", and DPT 11s "date"

• 4-Byte DPT 12s, DPT 13s, DPT 14s, DPT 15s "4-octet" (e.g. counter values)

• 14-Byte DPT 16s "String" (also known as 'Text', 'HexText')

The character sets supported by KNX are ASCII and ISO 8859-1.