The KNX Association is committed to guaranteeing interworking compatibility among products from various KNX manufacturers - both within specific application domains and across different application areas. To achieve this, it is essential that all KNX manufacturers adhere to the Interworking Model as detailed in Volume 3/7/1 during the design of their applications.
In some cases, a manufacturer may need to implement a group object for which an appropriate Datapoint Type (DPT) is not available in Volume 3/7/2. If this occurs, the manufacturer may propose a non-standardized DPT for approval, provided it complies with the KNX DPT design guidelines.
Such proposals must be submitted to the KNX System Department of KNX Association. If needed, the department may consult with the Working Group Interworking (WGI) to review the submission. The goal of this process is to allow the reuse of non-standard DPTs by other manufacturers and potentially pave the way for their future standardization.
How to submit a non-standardized Datapoint Type for approval?
- If a non-standardized datapoint type is implemented in your application program, then it first needs to be approved before submitting the KNX product in which this non-standard DPT is used for registration.
- A manufacturer can request approval of this non-standard DPT in his/her MyKNX account.
Further guidelines
- Request for approval of the non-standardized DPT in time; preferably at that stage you know that a non-standardized DPT will be required.
- Only a person having the role 'Member Certification Coordinator' or 'Member Certification Contributor' is able to submit a non-standardized DPT for approval in MyKNX.
- Fill out the online non-standardized DPT form as detailed as possible in English. If not, this may cause substantial delays in approval.
- Each request for approval of a non-standardized DPT will receive a unique ID from KNX Association.
- When creating your project in the Manufacturer Tool, make sure that for this specific non-standardized DPT, you leave the Datapoint Type field empty.
- When completing the non-standardized DPT information in the registration application in MyKNX, make sure to refer to the ID of the approved non-standardized DPT.
- One can only refer to its own approved non-standardized DPTs and not the approved non-standardized DPTs of other companies.
- If any non-standardized DPT disguised as a counter DPT (e.g., 5.010 (DPT_Value_1_Ucount) or any other counter value) is found by KNX Association or the KNX accredited test lab, you could face the consequence that any future update request of this application program (in which the same non-DPT is reused) will be rejected. This means that your customers who already make use of this non-DPT in their projects cannot reuse updated application programs, in which this non-standardized DPT then has to be replaced by a different coding.
- If a non-standardized DPT has been approved for application version x and is reused for the same product type with the same Functional Block in an application program with version x+1, then KNX Association will continue to register the updated application program without formal re-approval of the non-standardized DPT. The manufacturer can simply refer to the previously approved non-standardized DPT.
However, if it concerns a different product type with different Functional Blocks, then the KNX manufacturer shall submit this non-standardized DPT again for formal approval first. - Non-standardized DPTs should be designed with the intention to be reused by other manufacturers and possibly even standardized. Follow the DPT design guidelines in Volume 3/7/1 “Interworking Model” of the KNX Specifications and pay attention to the following when designing your DPT:
- Reuse encoding of fields that can be found in already existing standardized DPTs (see Volume 3/7/2) and do not “re-invent” the wheel.
- Think of the error handling. Is there an easy error handling possible?
- Do not conflict/overlap with standardized Datapoint types. This means that if for a certain functionality a standardized KNX solution exists, then this standardized DPT shall be implemented.
- Choose a data type with the appropriate length. Unused bits must be put at the most significant position (and not somewhere in the middle or at the beginning) and must be set to zero.
- If a non-standardized DPT is used next to a standardized DPT, and if this setting can be changed via the parameters, then it must be ensured that the default value of the parameter setting is set to the standardized DPT.
- If you can make a mathematical operation (larger than, smaller than, plus or minus) to the proposed encoding, this means that this is a counter value (uCount). Counter values are used to count things, e.g., how many times has a relay been switched on/off? “0: summer”, “1: autumn”, “2: winter”, “3: spring” is not a Counter value, as the expression “summer” is larger than "winter” does not make sense.
- If you cannot make mathematical operations to the proposed encoding, then most probably this is an Enumeration (N). Please note that in an Enumeration, you can have only one value possible active at the same time. If it is a Bit set/Boolean, you can have multiple values activated at the same time.